Glossary · word list
English terms: Science
1,612 words and terms, A–Z, from School Launch lessons. Each links to the lesson where it is taught.
#
100-year floodEnglish
A flood so big that it has a 1 in 100 chance of happening in any single year. It can happen two years in a row.
Grade 4 Earth Science: Weather and Water, Lesson 6.4 (grade 4) · High School Geology, Lesson 4.4 (grade 9–12)
A flood so big that it has a 1 in 100 chance of happening in any single year. It can happen two years in a row.
Grade 4 Earth Science: Weather and Water, Lesson 6.4 (grade 4) · High School Geology, Lesson 4.4 (grade 9–12)
A
ʻaʻāEnglish
(AH-ah) Hawaiian lava that cools into rough, sharp, crumbly chunks.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.4 (grade 2)
(AH-ah) Hawaiian lava that cools into rough, sharp, crumbly chunks.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.4 (grade 2)
abdomenEnglish
The back part of an insect’s body. It is often the biggest part.
Grade 2 Life Science: Animal Families, Lesson 6.1 (grade 2)
The back part of an insect’s body. It is often the biggest part.
Grade 2 Life Science: Animal Families, Lesson 6.1 (grade 2)
abrasionEnglish
The sandblasting of rock and other objects by wind-driven grains, strongest within a meter of the ground.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.3 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 6.4 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 4.4 (grade 6)
The sandblasting of rock and other objects by wind-driven grains, strongest within a meter of the ground.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.3 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 6.4 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 4.4 (grade 6)
absorbEnglish
To soak up, the way a sponge soaks up water. Slate absorbs very little water.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.3 (grade 3) · Grade 3 Life Science: Plants and Animals Together, Lesson 1.2 (grade 3)
To soak up, the way a sponge soaks up water. Slate absorbs very little water.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.3 (grade 3) · Grade 3 Life Science: Plants and Animals Together, Lesson 1.2 (grade 3)
abstractEnglish
A short paragraph at the front of a report, about 100 words, that tells what was studied, how, what was found and what it means.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.4 (grade 8)
A short paragraph at the front of a report, about 100 words, that tells what was studied, how, what was found and what it means.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.4 (grade 8)
accelerationEnglish
Speeding up, slowing down or changing direction. A falling object accelerates: it goes faster every second.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.4 (grade 5) · Grade 5 Engineering & Physics, Lesson 1.2 (grade 5) · Grade 6 Engineering & Physics, Lesson 1.1 (grade 6) · +3 more
Speeding up, slowing down or changing direction. A falling object accelerates: it goes faster every second.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.4 (grade 5) · Grade 5 Engineering & Physics, Lesson 1.2 (grade 5) · Grade 6 Engineering & Physics, Lesson 1.1 (grade 6) · +3 more
accelerator mass spectrometry (AMS)English
A method that counts carbon-14 atoms one by one with a particle accelerator and magnets, instead of waiting for them to decay. It needs only a few milligrams of carbon.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.3 (grade 7)
A method that counts carbon-14 atoms one by one with a particle accelerator and magnets, instead of waiting for them to decay. It needs only a few milligrams of carbon.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.3 (grade 7)
acid mine drainageEnglish
Acidic, iron-rich water that forms when pyrite (iron sulfide, FeS₂) in coal or overburden is exposed to oxygen and water. It can drop a stream’s pH below 4 and coat the bed with orange iron hydroxide.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.4 (grade 8)
Acidic, iron-rich water that forms when pyrite (iron sulfide, FeS₂) in coal or overburden is exposed to oxygen and water. It can drop a stream’s pH below 4 and coat the bed with orange iron hydroxide.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.4 (grade 8)
acoustic fatEnglish
Special fat inside the dolphin’s lower jaw that carries returning echoes back to the inner ear.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.2 (grade 6)
Special fat inside the dolphin’s lower jaw that carries returning echoes back to the inner ear.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.2 (grade 6)
acre-footEnglish
The volume of water that covers one acre to a depth of one foot, about 1,233 cubic meters (1.23 million liters). Western water agencies still state yearly amounts in acre-feet.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.4 (grade 8) · Human Geography, Lesson 9.2 (grade 9–12)
The volume of water that covers one acre to a depth of one foot, about 1,233 cubic meters (1.23 million liters). Western water agencies still state yearly amounts in acre-feet.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.4 (grade 8) · Human Geography, Lesson 9.2 (grade 9–12)
active sonarEnglish
Sonar that sends out its own sound pulse (a “ping”) and listens for the echo, as a bat or dolphin does.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.3 (grade 6)
Sonar that sends out its own sound pulse (a “ping”) and listens for the echo, as a bat or dolphin does.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.3 (grade 6)
adaptationEnglish
A body part or behavior that helps a living thing survive where it lives, such as a cactus’s waxy skin or a toucan’s long bill.
Grade 4 Earth Science: Weather and Water, Lesson 8.3 (grade 4) · Tactics & Strategy, Lesson 3.5 (grade 8–12) · Tactics & Strategy, Lesson 6.3 (grade 8–12) · +3 more
A body part or behavior that helps a living thing survive where it lives, such as a cactus’s waxy skin or a toucan’s long bill.
Grade 4 Earth Science: Weather and Water, Lesson 8.3 (grade 4) · Tactics & Strategy, Lesson 3.5 (grade 8–12) · Tactics & Strategy, Lesson 6.3 (grade 8–12) · +3 more
advection fogEnglish
Fog that forms when moist air blows over a cold surface, such as a cold ocean current, and is cooled to its dew point.
Grade 4 Earth Science: Weather and Water, Lesson 3.3 (grade 4)
Fog that forms when moist air blows over a cold surface, such as a cold ocean current, and is cooled to its dew point.
Grade 4 Earth Science: Weather and Water, Lesson 3.3 (grade 4)
affectedEnglish
Showing the trait being studied. Affected people are drawn as shaded symbols in a pedigree.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.4 (grade 8)
Showing the trait being studied. Affected people are drawn as shaded symbols in a pedigree.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.4 (grade 8)
after his kindEnglish
The Bible’s words for how living things make more of their own kind: bean seeds grow beans, and apple seeds grow apple trees (Genesis 1:11–12).
Grade 3 Life Science: Plants and Animals Together, Lesson 2.4 (grade 3)
The Bible’s words for how living things make more of their own kind: bean seeds grow beans, and apple seeds grow apple trees (Genesis 1:11–12).
Grade 3 Life Science: Plants and Animals Together, Lesson 2.4 (grade 3)
aftershockEnglish
A smaller shake that comes after a big earthquake.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.1 (grade 2) · Grade 6 Earth Science: The Dynamic Earth, Lesson 4.1 (grade 6)
A smaller shake that comes after a big earthquake.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.1 (grade 2) · Grade 6 Earth Science: The Dynamic Earth, Lesson 4.1 (grade 6)
airEnglish
The invisible stuff all around us that we breathe. We cannot see it, but it is real and it can push.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.1 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.2 (grade K) · Grade 1 Engineering & Physics, Lesson 7.1 (grade 1)
The invisible stuff all around us that we breathe. We cannot see it, but it is real and it can push.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.1 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.2 (grade K) · Grade 1 Engineering & Physics, Lesson 7.1 (grade 1)
air massEnglish
A huge body of air, often as wide as several states, that has about the same temperature and moisture all through it.
Grade 4 Earth Science: Weather and Water, Lesson 5.3 (grade 4)
A huge body of air, often as wide as several states, that has about the same temperature and moisture all through it.
Grade 4 Earth Science: Weather and Water, Lesson 5.3 (grade 4)
air resistanceEnglish
The push of air against a moving object. It slows light, spread-out objects like feathers and flat paper much more than heavy, compact ones.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.4 (grade 5) · Grade 1 Engineering & Physics, Lesson 7.2 (grade 1) · Grade 3 Life Science: Plants and Animals Together, Lesson 7.3 (grade 3)
The push of air against a moving object. It slows light, spread-out objects like feathers and flat paper much more than heavy, compact ones.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.4 (grade 5) · Grade 1 Engineering & Physics, Lesson 7.2 (grade 1) · Grade 3 Life Science: Plants and Animals Together, Lesson 7.3 (grade 3)
air sacsEnglish
Thin-walled, balloon-like bags connected to a bird’s lungs. They work like bellows, storing and pushing air, but oxygen does not pass into the blood there. Most birds have nine.
Grade 7 Life Science: Cells and Microbes, Lesson 7.2 (grade 7)
Thin-walled, balloon-like bags connected to a bird’s lungs. They work like bellows, storing and pushing air, but oxygen does not pass into the blood there. Most birds have nine.
Grade 7 Life Science: Cells and Microbes, Lesson 7.2 (grade 7)
airspeed and ground speedEnglish
Airspeed is how fast an aircraft moves through the air; ground speed is how fast it moves over the ground. A headwind makes airspeed greater than ground speed; lift depends on airspeed.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.3 (grade 8) · Technology Overcoming Geography, Lesson 4.3 (grade 9–12)
Airspeed is how fast an aircraft moves through the air; ground speed is how fast it moves over the ground. A headwind makes airspeed greater than ground speed; lift depends on airspeed.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.3 (grade 8) · Technology Overcoming Geography, Lesson 4.3 (grade 9–12)
algaeEnglish
Tiny green plant-like living things that grow in water. Some float like green threads or make the water look green.
Grade 1 Life Science: Animal Homes and Habits, Lesson 2.4 (grade 1) · Grade 3 Life Science: Plants and Animals Together, Lesson 5.3 (grade 3) · Grade 7 Life Science: Cells and Microbes, Lesson 3.2 (grade 7)
Tiny green plant-like living things that grow in water. Some float like green threads or make the water look green.
Grade 1 Life Science: Animal Homes and Habits, Lesson 2.4 (grade 1) · Grade 3 Life Science: Plants and Animals Together, Lesson 5.3 (grade 3) · Grade 7 Life Science: Cells and Microbes, Lesson 3.2 (grade 7)
alidadeEnglish
The sighting bar on the back of an astrolabe. It has two small holes or slits that you line up with a star.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.2 (grade 5) · Grade 5 Geography: Explorers, Navigators and Missionaries, Lesson 2.2 (grade 5)
The sighting bar on the back of an astrolabe. It has two small holes or slits that you line up with a star.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.2 (grade 5) · Grade 5 Geography: Explorers, Navigators and Missionaries, Lesson 2.2 (grade 5)
allomotherEnglish
A family member other than the mother, often a young female, who helps care for a calf.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.3 (grade 6)
A family member other than the mother, often a young female, who helps care for a calf.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.3 (grade 6)
alpine meadowEnglish
The cold, open land above the tree line, where only low plants grow: grass, tiny flowers, moss and lichens.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.4 (grade 2)
The cold, open land above the tree line, where only low plants grow: grass, tiny flowers, moss and lichens.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.4 (grade 2)
altimeter settingEnglish
The current sea-level pressure, which a pilot dials into the altimeter so it reads true altitude. Near sea level, each hectopascal of pressure is worth about 8 m of altitude.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.3 (grade 8)
The current sea-level pressure, which a pilot dials into the altimeter so it reads true altitude. Near sea level, each hectopascal of pressure is worth about 8 m of altitude.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.3 (grade 8)
alveoliEnglish
Tiny, thin-walled air sacs at the ends of the smallest airways, wrapped in blood vessels. Oxygen passes into the blood here.
Grade 5 Life Science: The Human Body, Lesson 4.1 (grade 5)
Tiny, thin-walled air sacs at the ends of the smallest airways, wrapped in blood vessels. Oxygen passes into the blood here.
Grade 5 Life Science: The Human Body, Lesson 4.1 (grade 5)
AmanitaEnglish
A group (genus) of mushrooms with white spore prints, often a ring on the stalk and a cup at the base. It includes the deadliest mushrooms in the world, such as the death cap.
Grade 7 Life Science: Cells and Microbes, Lesson 6.4 (grade 7)
A group (genus) of mushrooms with white spore prints, often a ring on the stalk and a cup at the base. It includes the deadliest mushrooms in the world, such as the death cap.
Grade 7 Life Science: Cells and Microbes, Lesson 6.4 (grade 7)
amatoxinEnglish
A group of deadly toxins found in death caps, destroying angels and some other mushrooms. Amatoxins stop cells from making proteins and destroy the liver. Cooking, freezing and drying do not remove them.
Grade 7 Life Science: Cells and Microbes, Lesson 6.4 (grade 7)
A group of deadly toxins found in death caps, destroying angels and some other mushrooms. Amatoxins stop cells from making proteins and destroy the liver. Cooking, freezing and drying do not remove them.
Grade 7 Life Science: Cells and Microbes, Lesson 6.4 (grade 7)
amplitudeEnglish
The height of the biggest wiggle on a seismogram; how far the ground moved.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.2 (grade 6) · Physics, Lesson 9.1 (grade 11–12) · Trigonometry, Lesson 4.3 (grade 11–12)
The height of the biggest wiggle on a seismogram; how far the ground moved.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.2 (grade 6) · Physics, Lesson 9.1 (grade 11–12) · Trigonometry, Lesson 4.3 (grade 11–12)
analogyEnglish
A comparison that explains something new by showing how it is like something familiar, such as “the nucleus is like an office that keeps the recipe book.”
Grade 7 Life Science: Cells and Microbes, Lesson 2.4 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.1 (grade 8)
A comparison that explains something new by showing how it is like something familiar, such as “the nucleus is like an office that keeps the recipe book.”
Grade 7 Life Science: Cells and Microbes, Lesson 2.4 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.1 (grade 8)
anatomical directionsEnglish
Words for locating parts on an animal’s body: anterior (head end), posterior (tail end), dorsal (back side) and ventral (belly side).
Grade 7 Life Science: Cells and Microbes, Lesson 8.4 (grade 7)
Words for locating parts on an animal’s body: anterior (head end), posterior (tail end), dorsal (back side) and ventral (belly side).
Grade 7 Life Science: Cells and Microbes, Lesson 8.4 (grade 7)
anatomistEnglish
A scientist who studies the structure of living bodies, usually by careful dissection and drawing.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.1 (grade 7) · Explore Dinosaurs · Ranger, Stop 2.4 (Ages 10–13) · Explore Dinosaurs, Stop 2.4 (Ages 7–9) · +1 more
A scientist who studies the structure of living bodies, usually by careful dissection and drawing.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.1 (grade 7) · Explore Dinosaurs · Ranger, Stop 2.4 (Ages 10–13) · Explore Dinosaurs, Stop 2.4 (Ages 7–9) · +1 more
aneroid barometerEnglish
A barometer with no liquid in it. A sealed metal box gets squeezed in or puffs out as air pressure changes, and a needle shows the change.
Grade 4 Earth Science: Weather and Water, Lesson 2.2 (grade 4)
A barometer with no liquid in it. A sealed metal box gets squeezed in or puffs out as air pressure changes, and a needle shows the change.
Grade 4 Earth Science: Weather and Water, Lesson 2.2 (grade 4)
angle of reposeEnglish
The steepest slope a pile of loose grains can hold before it slides. For dry sand it is about 32 to 34 degrees, the angle of every dune’s slip face.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.3 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 8.3 (grade 6) · Architecture & Civil Engineering, Lesson 1.2 (grade 9–12) · +1 more
The steepest slope a pile of loose grains can hold before it slides. For dry sand it is about 32 to 34 degrees, the angle of every dune’s slip face.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.3 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 8.3 (grade 6) · Architecture & Civil Engineering, Lesson 1.2 (grade 9–12) · +1 more
angular distanceEnglish
How far apart two things look in the sky, measured in degrees. A fist at arm’s length covers about 10°.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.2 (grade 5)
How far apart two things look in the sky, measured in degrees. A fist at arm’s length covers about 10°.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.2 (grade 5)
angular unconformityEnglish
An unconformity where the layers below are tilted and the layers above lie flat across their cut-off ends, as at Siccar Point, Scotland.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.2 (grade 7)
An unconformity where the layers below are tilted and the layers above lie flat across their cut-off ends, as at Siccar Point, Scotland.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.2 (grade 7)
animal familyEnglish
A big group of animals with bodies that are alike, such as birds (feathers) or mammals (fur and milk).
Grade 2 Life Science: Animal Families, Lesson 9.3 (grade 2)
A big group of animals with bodies that are alike, such as birds (feathers) or mammals (fur and milk).
Grade 2 Life Science: Animal Families, Lesson 9.3 (grade 2)
animalculeEnglish
“Little animal”: the English word used in the 1600s and 1700s for the tiny moving creatures Leeuwenhoek saw. Today we call them microorganisms.
Grade 7 Life Science: Cells and Microbes, Lesson 1.1 (grade 7)
“Little animal”: the English word used in the 1600s and 1700s for the tiny moving creatures Leeuwenhoek saw. Today we call them microorganisms.
Grade 7 Life Science: Cells and Microbes, Lesson 1.1 (grade 7)
annual layerEnglish
The band of ice thought to represent one year, usually a coarse summer layer and a fine winter layer, often marked by a spring dust peak.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.4 (grade 7)
The band of ice thought to represent one year, usually a coarse summer layer and a fine winter layer, often marked by a spring dust peak.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.4 (grade 7)
AntarcticaEnglish
The icy land around the South Pole, covered by a thick sheet of ice.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.4 (grade 2) · Explore Animals, Stop 2.4 (Ages 7–9) · Grade 1 Geography: Maps and Journeys, Lesson 7.4 (grade 1) · +1 more
The icy land around the South Pole, covered by a thick sheet of ice.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.4 (grade 2) · Explore Animals, Stop 2.4 (Ages 7–9) · Grade 1 Geography: Maps and Journeys, Lesson 7.4 (grade 1) · +1 more
antecedent riverEnglish
A river that kept its course by cutting down through land that rose beneath it.
High School Geology, Lesson 6.3 (grade 9–12)
A river that kept its course by cutting down through land that rose beneath it.
High School Geology, Lesson 6.3 (grade 9–12)
antennaeEnglish
Two feelers on an insect’s head. The insect uses them to touch and smell.
Grade 2 Life Science: Animal Families, Lesson 6.1 (grade 2) · Grade 3 Life Science: Plants and Animals Together, Lesson 3.2 (grade 3) · Kindergarten Life Science: God Made the Animals, Lesson 4.1 (grade K)
Two feelers on an insect’s head. The insect uses them to touch and smell.
Grade 2 Life Science: Animal Families, Lesson 6.1 (grade 2) · Grade 3 Life Science: Plants and Animals Together, Lesson 3.2 (grade 3) · Kindergarten Life Science: God Made the Animals, Lesson 4.1 (grade K)
anthraciteEnglish
The hardest, shiniest kind of coal. It has the most carbon and burns hot with little smoke.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.3 (grade 3)
The hardest, shiniest kind of coal. It has the most carbon and burns hot with little smoke.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.3 (grade 3)
anthropic principleEnglish
The idea that we can only observe a universe that allows observers like us to exist, so we should expect to find one fit for life. The name was given by the physicist Brandon Carter in 1973.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.4 (grade 8)
The idea that we can only observe a universe that allows observers like us to exist, so we should expect to find one fit for life. The name was given by the physicist Brandon Carter in 1973.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.4 (grade 8)
antibioticEnglish
A substance made by one living thing that kills or stops the growth of germs such as bacteria or harmful molds.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.4 (grade 6) · Grade 7 Life Science: Cells and Microbes, Lesson 4.3 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.3 (grade 8)
A substance made by one living thing that kills or stops the growth of germs such as bacteria or harmful molds.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.4 (grade 6) · Grade 7 Life Science: Cells and Microbes, Lesson 4.3 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.3 (grade 8)
antibiotic resistanceEnglish
The ability of some bacteria to survive an antibiotic. When the others die, the resistant ones multiply.
Grade 7 Life Science: Cells and Microbes, Lesson 4.3 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.3 (grade 8)
The ability of some bacteria to survive an antibiotic. When the others die, the resistant ones multiply.
Grade 7 Life Science: Cells and Microbes, Lesson 4.3 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.3 (grade 8)
antibodyEnglish
A Y-shaped protein made by white blood cells called B cells. Each kind fits one particular germ and marks it for destruction.
Grade 7 Life Science: Cells and Microbes, Lesson 4.4 (grade 7)
A Y-shaped protein made by white blood cells called B cells. Each kind fits one particular germ and marks it for destruction.
Grade 7 Life Science: Cells and Microbes, Lesson 4.4 (grade 7)
anticlineEnglish
An upward arch of folded rock layers, with the oldest layers in the center; a syncline is the matching downward trough.
High School Geology, Lesson 2.4 (grade 9–12)
An upward arch of folded rock layers, with the oldest layers in the center; a syncline is the matching downward trough.
High School Geology, Lesson 2.4 (grade 9–12)
anvilEnglish
The flat, spreading top of a tall cumulonimbus, shaped like a blacksmith’s anvil.
Grade 4 Earth Science: Weather and Water, Lesson 3.2 (grade 4) · Explore Animals · Expert, Stop 6.6 (Ages 14+) · Explore Animals · Ranger, Stop 6.6 (Ages 10–13) · +1 more
The flat, spreading top of a tall cumulonimbus, shaped like a blacksmith’s anvil.
Grade 4 Earth Science: Weather and Water, Lesson 3.2 (grade 4) · Explore Animals · Expert, Stop 6.6 (Ages 14+) · Explore Animals · Ranger, Stop 6.6 (Ages 10–13) · +1 more
aortic archesEnglish
Five pairs of muscular blood vessels near the front of the earthworm that pump blood from the dorsal vessel to the ventral vessel. They are often called the worm’s “hearts.”
Grade 7 Life Science: Cells and Microbes, Lesson 8.1 (grade 7)
Five pairs of muscular blood vessels near the front of the earthworm that pump blood from the dorsal vessel to the ventral vessel. They are often called the worm’s “hearts.”
Grade 7 Life Science: Cells and Microbes, Lesson 8.1 (grade 7)
apeEnglish
A primate with no tail, long arms and a large brain. Gibbons, orangutans, gorillas, chimpanzees and bonobos are apes.
Grade 4 Life Science: Classification, Lesson 5.3 (grade 4)
A primate with no tail, long arms and a large brain. Gibbons, orangutans, gorillas, chimpanzees and bonobos are apes.
Grade 4 Life Science: Classification, Lesson 5.3 (grade 4)
apertureEnglish
The width of a telescope’s main lens or mirror. A bigger aperture gathers more light.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.3 (grade 5)
The width of a telescope’s main lens or mirror. A bigger aperture gathers more light.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.3 (grade 5)
approximate original contourEnglish
The shape the law requires reclaimed land to have: highwalls and spoil piles eliminated and slopes regraded so the land closely resembles its shape before mining and drains the way it did.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.4 (grade 8)
The shape the law requires reclaimed land to have: highwalls and spoil piles eliminated and slopes regraded so the land closely resembles its shape before mining and drains the way it did.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.4 (grade 8)
aquiferEnglish
A layer of sand, gravel or cracked rock that holds groundwater and lets it flow out to wells and springs.
Grade 4 Earth Science: Weather and Water, Lesson 1.4 (grade 4) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.2 (grade 8) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 3.3 (grade 4) · +2 more
A layer of sand, gravel or cracked rock that holds groundwater and lets it flow out to wells and springs.
Grade 4 Earth Science: Weather and Water, Lesson 1.4 (grade 4) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.2 (grade 8) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 3.3 (grade 4) · +2 more
ArcticEnglish
The cold area around the North Pole, mostly an ocean covered with floating sea ice.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.4 (grade 2) · Grade 1 Geography: Maps and Journeys, Lesson 5.2 (grade 1) · Grade 1 Life Science: Animal Homes and Habits, Lesson 5.1 (grade 1)
The cold area around the North Pole, mostly an ocean covered with floating sea ice.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.4 (grade 2) · Grade 1 Geography: Maps and Journeys, Lesson 5.2 (grade 1) · Grade 1 Life Science: Animal Homes and Habits, Lesson 5.1 (grade 1)
Arctic CircleEnglish
The line of latitude 66.5° north. North of it, the Sun does not set on the June solstice and does not rise on the December solstice.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.2 (grade 5) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 4.4 (grade 4)
The line of latitude 66.5° north. North of it, the Sun does not set on the June solstice and does not rise on the December solstice.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.2 (grade 5) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 4.4 (grade 4)
arkEnglish
The big wooden boat God told Noah to build to save his family and the animals from the Flood.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.3 (grade 2) · Grade 2 Earth Science: The Earth's Surface, Lesson 7.4 (grade 2) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 3.4 (grade K) · +3 more
The big wooden boat God told Noah to build to save his family and the animals from the Flood.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.3 (grade 2) · Grade 2 Earth Science: The Earth's Surface, Lesson 7.4 (grade 2) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 3.4 (grade K) · +3 more
ark of the covenantEnglish
The special chest covered with gold that held the tablets of God’s law. Priests carried it on poles.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.4 (grade 1) · Explore Great Battles · Ranger, Stop 1.8 (Ages 10–13)
The special chest covered with gold that held the tablets of God’s law. Priests carried it on poles.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.4 (grade 1) · Explore Great Battles · Ranger, Stop 1.8 (Ages 10–13)
arteryEnglish
A thick-walled blood vessel that carries blood away from the heart.
Grade 5 Life Science: The Human Body, Lesson 3.1 (grade 5) · Grade 5 Physical Education & Health, Lesson 5.1 (grade 5)
A thick-walled blood vessel that carries blood away from the heart.
Grade 5 Life Science: The Human Body, Lesson 3.1 (grade 5) · Grade 5 Physical Education & Health, Lesson 5.1 (grade 5)
artesian wellEnglish
A well drilled into a confined aquifer in which pressure pushes water up above the top of the aquifer, sometimes all the way to the surface.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.2 (grade 8) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.2 (grade 8)
A well drilled into a confined aquifer in which pressure pushes water up above the top of the aquifer, sometimes all the way to the surface.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.2 (grade 8) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.2 (grade 8)
arthropodEnglish
An invertebrate with jointed legs, a hard outer covering and a body made of segments. Insects, spiders and crabs are arthropods.
Grade 4 Life Science: Classification, Lesson 3.1 (grade 4)
An invertebrate with jointed legs, a hard outer covering and a body made of segments. Insects, spiders and crabs are arthropods.
Grade 4 Life Science: Classification, Lesson 3.1 (grade 4)
articulatedEnglish
Bones still joined in life position, as in Douglass’s row of eight tail vertebrae. Articulated bones mean the body was buried before it fell apart.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.2 (grade 6) · Explore Dinosaurs · Ranger, Stop 4.5 (Ages 10–13)
Bones still joined in life position, as in Douglass’s row of eight tail vertebrae. Articulated bones mean the body was buried before it fell apart.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.2 (grade 6) · Explore Dinosaurs · Ranger, Stop 4.5 (Ages 10–13)
artificial selectionEnglish
Selective breeding: people choose which animals or plants become parents in order to make certain traits more common.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.2 (grade 8)
Selective breeding: people choose which animals or plants become parents in order to make certain traits more common.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.2 (grade 8)
asepticEnglish
Germ-free. Aseptic surgery keeps germs out from the start with sterilized tools, clean gowns, masks and gloves.
Grade 5 Life Science: The Human Body, Lesson 8.3 (grade 5)
Germ-free. Aseptic surgery keeps germs out from the start with sterilized tools, clean gowns, masks and gloves.
Grade 5 Life Science: The Human Body, Lesson 8.3 (grade 5)
aseptic techniqueEnglish
Careful habits that keep unwanted microbes out of a culture and keep the culture from escaping: clean hands and surfaces, sterile tools, lids kept closed.
Grade 7 Life Science: Cells and Microbes, Lesson 3.4 (grade 7)
Careful habits that keep unwanted microbes out of a culture and keep the culture from escaping: clean hands and surfaces, sterile tools, lids kept closed.
Grade 7 Life Science: Cells and Microbes, Lesson 3.4 (grade 7)
ashEnglish
Tiny bits of broken rock and glass blown out of a volcano. It looks like gray powder, but it is gritty like sand, not soft like wood ash.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.1 (grade 2)
Tiny bits of broken rock and glass blown out of a volcano. It looks like gray powder, but it is gritty like sand, not soft like wood ash.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.1 (grade 2)
asterismEnglish
A well-known star pattern that is not one of the 88 official constellations, such as the Big Dipper or Orion’s belt.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.2 (grade 5)
A well-known star pattern that is not one of the 88 official constellations, such as the Big Dipper or Orion’s belt.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.2 (grade 5)
asthenosphereEnglish
The hot, soft zone of the upper mantle just below the lithosphere. It is solid but can flow slowly, so the plates can move over it.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.2 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 2.3 (grade 6)
The hot, soft zone of the upper mantle just below the lithosphere. It is solid but can flow slowly, so the plates can move over it.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.2 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 2.3 (grade 6)
astrolabeEnglish
An old instrument, usually made of brass, used to measure the altitude of the sun or a star and to work out the time, latitude and other sky facts.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.2 (grade 5)
An old instrument, usually made of brass, used to measure the altitude of the sun or a star and to work out the time, latitude and other sky facts.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.2 (grade 5)
astronautEnglish
A person who is trained to travel into space.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.3 (grade 1)
A person who is trained to travel into space.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.3 (grade 1)
astronomerEnglish
A scientist who studies the Sun, Moon, planets, stars and everything else in the sky.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.1 (grade 5)
A scientist who studies the Sun, Moon, planets, stars and everything else in the sky.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.1 (grade 5)
astronomical unit (AU)English
The average distance from Earth to the Sun, about 150 million kilometers (93 million miles). Astronomers use it as a measuring stick for the solar system.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.2 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.4 (grade 5) · Physics, Lesson 4.3 (grade 11–12)
The average distance from Earth to the Sun, about 150 million kilometers (93 million miles). Astronomers use it as a measuring stick for the solar system.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.2 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.4 (grade 5) · Physics, Lesson 4.3 (grade 11–12)
asymmetrical featherEnglish
A feather whose shaft is off center, with a narrow leading vane and a wide trailing vane. Flying birds have them in their wings; they help the feather work like a small wing.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.3 (grade 8)
A feather whose shaft is off center, with a narrow leading vane and a wide trailing vane. Flying birds have them in their wings; they help the feather work like a small wing.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.3 (grade 8)
atomEnglish
One of the tiny building blocks that everything is made of, far too small to see even with a microscope at home.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.4 (grade 3)
One of the tiny building blocks that everything is made of, far too small to see even with a microscope at home.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.4 (grade 3)
atrium and ventricleEnglish
The chambers of the heart. An atrium (plural atria) receives blood coming in; a ventricle pumps blood out. A frog has two atria and one ventricle.
Grade 7 Life Science: Cells and Microbes, Lesson 8.2 (grade 7)
The chambers of the heart. An atrium (plural atria) receives blood coming in; a ventricle pumps blood out. A frog has two atria and one ventricle.
Grade 7 Life Science: Cells and Microbes, Lesson 8.2 (grade 7)
attribute tableEnglish
The spreadsheet behind a vector layer: one row for each feature and one column for each fact about it, such as a well’s depth or a unit’s rock type.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.3 (grade 8)
The spreadsheet behind a vector layer: one row for each feature and one column for each fact about it, such as a well’s depth or a unit’s rock type.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.3 (grade 8)
autosomal traitEnglish
A trait whose gene lies on one of the chromosomes that are the same in males and females (the autosomes), so it is inherited the same way by sons and daughters.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.4 (grade 8)
A trait whose gene lies on one of the chromosomes that are the same in males and females (the autosomes), so it is inherited the same way by sons and daughters.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.4 (grade 8)
averageEnglish
A number that stands for a whole group of numbers, found by adding them all and dividing by how many there are. Also called the mean.
Grade 4 Earth Science: Weather and Water, Lesson 8.4 (grade 4) · Grade 5 Life Science: The Human Body, Lesson 9.2 (grade 5)
A number that stands for a whole group of numbers, found by adding them all and dividing by how many there are. Also called the mean.
Grade 4 Earth Science: Weather and Water, Lesson 8.4 (grade 4) · Grade 5 Life Science: The Human Body, Lesson 9.2 (grade 5)
average (mean)English
The sum of several measurements divided by how many there are. Averaging several trials gives a more trustworthy result.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.4 (grade 6)
The sum of several measurements divided by how many there are. Averaging several trials gives a more trustworthy result.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.4 (grade 6)
averted visionEnglish
Looking slightly to one side of a faint object so its light falls on the part of the eye that sees best in dim light.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.4 (grade 5)
Looking slightly to one side of a faint object so its light falls on the part of the eye that sees best in dim light.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.4 (grade 5)
axisEnglish
An imaginary line through the North and South Poles that the earth spins around.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.3 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.1 (grade 5) · Grade 3 Gardening & Animals, Lesson 1.1 (grade 3) · +2 more
An imaginary line through the North and South Poles that the earth spins around.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.3 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.1 (grade 5) · Grade 3 Gardening & Animals, Lesson 1.1 (grade 3) · +2 more
B
baby plantEnglish
The tiny plant tucked inside every seed, with a little root and two folded leaves.
Kindergarten Life Science: God Made the Animals, Lesson 5.1 (grade K)
The tiny plant tucked inside every seed, with a little root and two folded leaves.
Kindergarten Life Science: God Made the Animals, Lesson 5.1 (grade K)
backboneEnglish
The chain of vertebrae that runs down the middle of a vertebrate’s back. It is also called the spine or spinal column.
Grade 4 Life Science: Classification, Lesson 2.2 (grade 4)
The chain of vertebrae that runs down the middle of a vertebrate’s back. It is also called the spine or spinal column.
Grade 4 Life Science: Classification, Lesson 2.2 (grade 4)
background matchingEnglish
Camouflage in which an animal’s colors and pattern match the place where it lives, like a brown moth on brown bark.
Grade 6 Life Science: Animal Design and Behavior, Lesson 4.4 (grade 6)
Camouflage in which an animal’s colors and pattern match the place where it lives, like a brown moth on brown bark.
Grade 6 Life Science: Animal Design and Behavior, Lesson 4.4 (grade 6)
bacterium (plural: bacteria)English
A single-celled living thing with no nucleus. Its DNA lies loose in the cytoplasm in a region called the nucleoid.
Grade 7 Life Science: Cells and Microbes, Lesson 3.1 (grade 7)
A single-celled living thing with no nucleus. Its DNA lies loose in the cytoplasm in a region called the nucleoid.
Grade 7 Life Science: Cells and Microbes, Lesson 3.1 (grade 7)
bacterium (plural bacteria)English
A single-celled living thing with no nucleus. Most bacteria are harmless or helpful; a few cause disease.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.3 (grade 8)
A single-celled living thing with no nucleus. Most bacteria are harmless or helpful; a few cause disease.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.3 (grade 8)
Bactrian camelEnglish
A camel with two humps and a thick, shaggy winter coat. Bactrian camels live in the deserts of Asia, where winters are very cold.
Grade 1 Life Science: Animal Homes and Habits, Lesson 4.1 (grade 1)
A camel with two humps and a thick, shaggy winter coat. Bactrian camels live in the deserts of Asia, where winters are very cold.
Grade 1 Life Science: Animal Homes and Habits, Lesson 4.1 (grade 1)
bag limitEnglish
The number of a game animal one hunter may legally take in a day or a season.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 7.4 (grade 8) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.2 (grade 8)
The number of a game animal one hunter may legally take in a day or a season.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 7.4 (grade 8) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.2 (grade 8)
baked zoneEnglish
A band of rock next to a dike or sill that was heated and hardened by the molten rock; it proves the intrusion was hot and came later.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.4 (grade 7)
A band of rock next to a dike or sill that was heated and hardened by the molten rock; it proves the intrusion was hot and came later.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.4 (grade 7)
bandEnglish
A tiny metal ring put on a bird’s leg with a number on it, so people can know that bird if they find it again.
Grade 2 Life Science: Animal Families, Lesson 2.4 (grade 2) · Grade 3 Life Science: Plants and Animals Together, Lesson 6.3 (grade 3)
A tiny metal ring put on a bird’s leg with a number on it, so people can know that bird if they find it again.
Grade 2 Life Science: Animal Families, Lesson 2.4 (grade 2) · Grade 3 Life Science: Plants and Animals Together, Lesson 6.3 (grade 3)
banksEnglish
The sides of a river, where the land meets the water.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.4 (grade 1)
The sides of a river, where the land meets the water.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.4 (grade 1)
barbs and barbulesEnglish
Barbs are the branches off the rachis; barbules are tiny side branches off each barb, with hooklets that zip neighboring barbs together into a flat vane.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.4 (grade 7) · Explore Dinosaurs · Ranger, Stop 3.7 (Ages 10–13)
Barbs are the branches off the rachis; barbules are tiny side branches off each barb, with hooklets that zip neighboring barbs together into a flat vane.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.4 (grade 7) · Explore Dinosaurs · Ranger, Stop 3.7 (Ages 10–13)
barographEnglish
An instrument that draws a continuous line of air pressure on a slowly turning paper drum.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.2 (grade 6)
An instrument that draws a continuous line of air pressure on a slowly turning paper drum.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.2 (grade 6)
barometerEnglish
An instrument that measures air pressure. The name comes from Greek words meaning “weight measure.”
Grade 4 Earth Science: Weather and Water, Lesson 2.1 (grade 4) · Physics, Lesson 8.1 (grade 11–12)
An instrument that measures air pressure. The name comes from Greek words meaning “weight measure.”
Grade 4 Earth Science: Weather and Water, Lesson 2.1 (grade 4) · Physics, Lesson 8.1 (grade 11–12)
basaltEnglish
A dark gray or black igneous rock with crystals too small to see. It cooled quickly from lava on or near the surface.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.2 (grade 3)
A dark gray or black igneous rock with crystals too small to see. It cooled quickly from lava on or near the surface.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.2 (grade 3)
base isolationEnglish
Setting a building on flexible bearings, often layers of rubber and steel with a lead core, so the ground can slide beneath it while the building moves much less.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.1 (grade 6) · Grade 4 Engineering & Physics, Lesson 3.4 (grade 4) · Grade 5 Engineering & Physics, Lesson 3.4 (grade 5) · +1 more
Setting a building on flexible bearings, often layers of rubber and steel with a lead core, so the ground can slide beneath it while the building moves much less.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.1 (grade 6) · Grade 4 Engineering & Physics, Lesson 3.4 (grade 4) · Grade 5 Engineering & Physics, Lesson 3.4 (grade 5) · +1 more
base levelEnglish
The lowest level to which a stream can erode its channel; ultimately sea level.
High School Geology, Lesson 3.2 (grade 9–12)
The lowest level to which a stream can erode its channel; ultimately sea level.
High School Geology, Lesson 3.2 (grade 9–12)
base mapEnglish
A map that other information is drawn on or compared with; for the capstone the topographic, geologic and soil maps are the three base maps.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.1 (grade 8) · Explore Travel and Faraway Places · Expert, Stop 1.8 (Ages 14+)
A map that other information is drawn on or compared with; for the capstone the topographic, geologic and soil maps are the three base maps.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.1 (grade 8) · Explore Travel and Faraway Places · Expert, Stop 1.8 (Ages 14+)
base pairEnglish
Two bases joined across the middle of the DNA ladder by hydrogen bonds. A always pairs with T, and G always pairs with C; the two strands are called complementary.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.1 (grade 8)
Two bases joined across the middle of the DNA ladder by hydrogen bonds. A always pairs with T, and G always pairs with C; the two strands are called complementary.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.1 (grade 8)
basidium (plural basidia)English
A tiny club-shaped cell on the gills of most mushrooms that makes spores at its tip, usually four but in some kinds two.
Grade 7 Life Science: Cells and Microbes, Lesson 6.3 (grade 7)
A tiny club-shaped cell on the gills of most mushrooms that makes spores at its tip, usually four but in some kinds two.
Grade 7 Life Science: Cells and Microbes, Lesson 6.3 (grade 7)
baskingEnglish
Lying in the sun to warm the body, as lizards, snakes and turtles do.
Grade 4 Life Science: Classification, Lesson 2.3 (grade 4)
Lying in the sun to warm the body, as lizards, snakes and turtles do.
Grade 4 Life Science: Classification, Lesson 2.3 (grade 4)
Batesian mimicryEnglish
When a harmless, tasty animal looks like a dangerous or bad-tasting one, and so is avoided. Named for Henry Walter Bates.
Grade 6 Life Science: Animal Design and Behavior, Lesson 4.3 (grade 6)
When a harmless, tasty animal looks like a dangerous or bad-tasting one, and so is avoided. Named for Henry Walter Bates.
Grade 6 Life Science: Animal Design and Behavior, Lesson 4.3 (grade 6)
batholithEnglish
A huge body of granite that cooled slowly underground from magma and was later exposed by uplift and erosion, as in the Sierra Nevada.
High School Geology, Lesson 2.4 (grade 9–12)
A huge body of granite that cooled slowly underground from magma and was later exposed by uplift and erosion, as in the Sierra Nevada.
High School Geology, Lesson 2.4 (grade 9–12)
bayEnglish
A part of the sea that reaches into the land, with land on three sides.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.1 (grade 2) · Architecture & Civil Engineering, Lesson 7.1 (grade 9–12) · Explore Horses and Ponies · Expert, Stop 1.8 (Ages 14+) · +3 more
A part of the sea that reaches into the land, with land on three sides.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.1 (grade 2) · Architecture & Civil Engineering, Lesson 7.1 (grade 9–12) · Explore Horses and Ponies · Expert, Stop 1.8 (Ages 14+) · +3 more
Bayer letterEnglish
A Greek letter given to a star in a constellation, usually starting with α (alpha) for the brightest. Polaris is Alpha Ursae Minoris, “alpha of the Little Bear.”
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.2 (grade 5)
A Greek letter given to a star in a constellation, usually starting with α (alpha) for the brightest. Polaris is Alpha Ursae Minoris, “alpha of the Little Bear.”
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.2 (grade 5)
bearingEnglish
The compass direction from one point to another, given in degrees clockwise from north.
Grade 7 Earth Science: Earth History and the Flood, Lesson 9.2 (grade 7) · Grade 2 Engineering & Physics, Lesson 9.4 (grade 2) · Explore Travel and Faraway Places · Expert, Stop 1.2 (Ages 14+) · +3 more
The compass direction from one point to another, given in degrees clockwise from north.
Grade 7 Earth Science: Earth History and the Flood, Lesson 9.2 (grade 7) · Grade 2 Engineering & Physics, Lesson 9.4 (grade 2) · Explore Travel and Faraway Places · Expert, Stop 1.2 (Ages 14+) · +3 more
bedEnglish
A single layer of sedimentary rock, also called a stratum. Beds can be thinner than a finger or thicker than a house.
Grade 7 Earth Science: Earth History and the Flood, Lesson 9.1 (grade 7)
A single layer of sedimentary rock, also called a stratum. Beds can be thinner than a finger or thicker than a house.
Grade 7 Earth Science: Earth History and the Flood, Lesson 9.1 (grade 7)
bedding planeEnglish
The flat surface that separates one layer (bed) from the next; it marks the top of one layer and the bottom of the one above.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.2 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 9.1 (grade 7)
The flat surface that separates one layer (bed) from the next; it marks the top of one layer and the bottom of the one above.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.2 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 9.1 (grade 7)
bedrockEnglish
The hard, solid rock deep under the soil and sand.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 2.4 (grade 1)
The hard, solid rock deep under the soil and sand.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 2.4 (grade 1)
BehemothEnglish
A huge, strong animal God told Job about in Job 40. Say it: bee-HEE-moth.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 7.4 (grade K) · Explore Animals · Expert, Stop 1.2 (Ages 14+) · Explore Dinosaurs · Expert, Stop 4.2 (Ages 14+) · +3 more
A huge, strong animal God told Job about in Job 40. Say it: bee-HEE-moth.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 7.4 (grade K) · Explore Animals · Expert, Stop 1.2 (Ages 14+) · Explore Dinosaurs · Expert, Stop 4.2 (Ages 14+) · +3 more
benchEnglish
One of the flat steps cut around the walls of an open pit; trucks drive on them and drills and shovels work from them. Each is typically 10 to 15 m tall.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.2 (grade 8)
One of the flat steps cut around the walls of an open pit; trucks drive on them and drills and shovels work from them. Each is typically 10 to 15 m tall.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.2 (grade 8)
beneficial useEnglish
A recognized useful purpose for water, such as irrigation, drinking, livestock, industry or mining. A western water right is for a measured amount for a stated use, and a right not used can be lost.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.4 (grade 8)
A recognized useful purpose for water, such as irrigation, drinking, livestock, industry or mining. A western water right is for a measured amount for a stated use, and a right not used can be lost.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.4 (grade 8)
Big DipperEnglish
Seven bright stars that make the shape of a big scoop with a bowl and a long handle.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 5.4 (grade K)
Seven bright stars that make the shape of a big scoop with a bowl and a long handle.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 5.4 (grade K)
binocularsEnglish
Two small telescopes joined side by side, one for each eye. “10×50” means they magnify 10 times and each front lens is 50 millimeters wide.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.4 (grade 5) · Explore Animals, Stop 2.10 (Ages 7–9) · Grade 2 Gardening & Animals, Lesson 2.1 (grade 2)
Two small telescopes joined side by side, one for each eye. “10×50” means they magnify 10 times and each front lens is 50 millimeters wide.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.4 (grade 5) · Explore Animals, Stop 2.10 (Ages 7–9) · Grade 2 Gardening & Animals, Lesson 2.1 (grade 2)
binomial nomenclatureEnglish
Linnaeus’s system of naming each species with two words. “Binomial” means “two names,” and “nomenclature” means “a system of naming.”
Grade 4 Life Science: Classification, Lesson 1.3 (grade 4)
Linnaeus’s system of naming each species with two words. “Binomial” means “two names,” and “nomenclature” means “a system of naming.”
Grade 4 Life Science: Classification, Lesson 1.3 (grade 4)
BioBlitzEnglish
An event where scientists and volunteers try to find and identify as many kinds of living things as they can in one place in a short time.
Grade 4 Life Science: Classification, Lesson 9.2 (grade 4)
An event where scientists and volunteers try to find and identify as many kinds of living things as they can in one place in a short time.
Grade 4 Life Science: Classification, Lesson 9.2 (grade 4)
biofoulingEnglish
The slime, algae and barnacles that grow on things left in water, such as ship hulls and docks.
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.2 (grade 6)
The slime, algae and barnacles that grow on things left in water, such as ship hulls and docks.
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.2 (grade 6)
biogenesisEnglish
The principle that living things come only from other living things.
Grade 7 Life Science: Cells and Microbes, Lesson 4.2 (grade 7)
The principle that living things come only from other living things.
Grade 7 Life Science: Cells and Microbes, Lesson 4.2 (grade 7)
biological drawingEnglish
A clear, accurate pencil drawing of a specimen made from life, with ruled label lines, a title, the magnification and a scale.
Grade 7 Life Science: Cells and Microbes, Lesson 1.4 (grade 7)
A clear, accurate pencil drawing of a specimen made from life, with ruled label lines, a title, the magnification and a scale.
Grade 7 Life Science: Cells and Microbes, Lesson 1.4 (grade 7)
bird-hippedEnglish
A dinosaur whose pubis bone points backward toward the tail, like a bird’s.
Grade 2 Life Science: Animal Families, Lesson 7.1 (grade 2)
A dinosaur whose pubis bone points backward toward the tail, like a bird’s.
Grade 2 Life Science: Animal Families, Lesson 7.1 (grade 2)
black lungEnglish
Coal workers’ pneumoconiosis, a disease caused by years of breathing fine coal dust. It is prevented by water sprays, ventilation and limits on dust in the air.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.3 (grade 8)
Coal workers’ pneumoconiosis, a disease caused by years of breathing fine coal dust. It is prevented by water sprays, ventilation and limits on dust in the air.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.3 (grade 8)
blizzardEnglish
A winter storm with strong winds of at least 56 km/h (35 mph) and falling or blowing snow that makes it hard to see farther than 400 m (1/4 mile) for 3 hours or more.
Grade 4 Earth Science: Weather and Water, Lesson 4.3 (grade 4)
A winter storm with strong winds of at least 56 km/h (35 mph) and falling or blowing snow that makes it hard to see farther than 400 m (1/4 mile) for 3 hours or more.
Grade 4 Earth Science: Weather and Water, Lesson 4.3 (grade 4)
blood bankEnglish
A place where donated blood is tested, separated into parts, labeled and stored until a patient needs it.
Grade 5 Life Science: The Human Body, Lesson 3.4 (grade 5)
A place where donated blood is tested, separated into parts, labeled and stored until a patient needs it.
Grade 5 Life Science: The Human Body, Lesson 3.4 (grade 5)
blood typeEnglish
The group a person’s blood belongs to (A, B, AB or O), set by markers on the red blood cells. Blood must be matched before a transfusion.
Grade 5 Life Science: The Human Body, Lesson 3.4 (grade 5)
The group a person’s blood belongs to (A, B, AB or O), set by markers on the red blood cells. Blood must be matched before a transfusion.
Grade 5 Life Science: The Human Body, Lesson 3.4 (grade 5)
blood vesselEnglish
A tiny tube that carries blood through the body, even through the inside of bones.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.4 (grade 3) · Explore Dinosaurs, Stop 2.10 (Ages 7–9)
A tiny tube that carries blood through the body, even through the inside of bones.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.4 (grade 3) · Explore Dinosaurs, Stop 2.10 (Ages 7–9)
body fossilEnglish
A fossil of part of the living thing itself, such as a bone, tooth, shell or piece of wood.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.2 (grade 3)
A fossil of part of the living thing itself, such as a bone, tooth, shell or piece of wood.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.2 (grade 3)
body heatEnglish
The warmth your own body makes all the time.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 8.2 (grade 1)
The warmth your own body makes all the time.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 8.2 (grade 1)
body planEnglish
The basic layout of an animal: its symmetry, segments, skeleton, gut, limbs and nerve cord.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.1 (grade 8)
The basic layout of an animal: its symmetry, segments, skeleton, gut, limbs and nerve cord.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.1 (grade 8)
body temperatureEnglish
How warm the inside of an animal’s body is, measured with a thermometer in degrees Celsius (°C) or Fahrenheit (°F).
Grade 4 Life Science: Classification, Lesson 2.3 (grade 4) · Grade 3 Physical Education & Health, Lesson 2.1 (grade 3)
How warm the inside of an animal’s body is, measured with a thermometer in degrees Celsius (°C) or Fahrenheit (°F).
Grade 4 Life Science: Classification, Lesson 2.3 (grade 4) · Grade 3 Physical Education & Health, Lesson 2.1 (grade 3)
boneEnglish
A hard, living body part made of minerals such as calcium and a tough, bendy material called collagen.
Grade 5 Life Science: The Human Body, Lesson 2.2 (grade 5) · Kindergarten Life Science: God Made the Animals, Lesson 6.2 (grade K) · Grade 2 Physical Education & Health, Lesson 4.1 (grade 2) · +1 more
A hard, living body part made of minerals such as calcium and a tough, bendy material called collagen.
Grade 5 Life Science: The Human Body, Lesson 2.2 (grade 5) · Kindergarten Life Science: God Made the Animals, Lesson 6.2 (grade K) · Grade 2 Physical Education & Health, Lesson 4.1 (grade 2) · +1 more
bone marrowEnglish
The soft tissue inside many bones. Red marrow makes new blood cells.
Grade 5 Life Science: The Human Body, Lesson 2.2 (grade 5) · Grade 5 Life Science: The Human Body, Lesson 3.3 (grade 5)
The soft tissue inside many bones. Red marrow makes new blood cells.
Grade 5 Life Science: The Human Body, Lesson 2.2 (grade 5) · Grade 5 Life Science: The Human Body, Lesson 3.3 (grade 5)
bony platesEnglish
Flat pieces of bone that grew in the skin of armored dinosaurs, fitting together like tiles.
Grade 2 Life Science: Animal Families, Lesson 7.2 (grade 2)
Flat pieces of bone that grew in the skin of armored dinosaurs, fitting together like tiles.
Grade 2 Life Science: Animal Families, Lesson 7.2 (grade 2)
boomtownEnglish
A town that grows very fast when a resource is found nearby. Beaumont grew from about 9,000 people to about 50,000 within months of the gusher.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.2 (grade 8) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 4.1 (grade 4)
A town that grows very fast when a resource is found nearby. Beaumont grew from about 9,000 people to about 50,000 within months of the gusher.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.2 (grade 8) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 4.1 (grade 4)
botanyEnglish
The study of plants. A person who studies plants is a botanist.
Grade 4 Life Science: Classification, Lesson 1.1 (grade 4)
The study of plants. A person who studies plants is a botanist.
Grade 4 Life Science: Classification, Lesson 1.1 (grade 4)
boulderEnglish
A very big rock, bigger than a basketball. Some boulders are as big as a car or a house.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 1.3 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 5.2 (grade 2)
A very big rock, bigger than a basketball. Some boulders are as big as a car or a house.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 1.3 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 5.2 (grade 2)
braceEnglish
A slanted piece that goes from corner to corner in a frame and makes a triangle, so the frame cannot lean.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.3 (grade 2) · Grade 1 Engineering & Physics, Lesson 3.2 (grade 1) · Kindergarten Engineering & Physics, Lesson 3.2 (grade K) · +2 more
A slanted piece that goes from corner to corner in a frame and makes a triangle, so the frame cannot lean.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.3 (grade 2) · Grade 1 Engineering & Physics, Lesson 3.2 (grade 1) · Kindergarten Engineering & Physics, Lesson 3.2 (grade K) · +2 more
brachiopodEnglish
A sea animal with two shells, like a clam but built differently, very common as a fossil in limestone.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.4 (grade 6)
A sea animal with two shells, like a clam but built differently, very common as a fossil in limestone.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.4 (grade 6)
brackish waterEnglish
Water that is a little salty, saltier than fresh water but less salty than the sea, as where a river meets the ocean.
Grade 4 Earth Science: Weather and Water, Lesson 7.3 (grade 4) · Geopolitics: The Great Ideas, Lesson 5.2 (grade 9–12) · Grade 7 Geography: Regions of the World, Lesson 2.2 (grade 7)
Water that is a little salty, saltier than fresh water but less salty than the sea, as where a river meets the ocean.
Grade 4 Earth Science: Weather and Water, Lesson 7.3 (grade 4) · Geopolitics: The Great Ideas, Lesson 5.2 (grade 9–12) · Grade 7 Geography: Regions of the World, Lesson 2.2 (grade 7)
BrailleEnglish
A way of reading with your fingers by feeling little raised dots on paper.
Grade 1 Life Science: Animal Homes and Habits, Lesson 8.4 (grade 1) · Grade 5 Life Science: The Human Body, Lesson 7.4 (grade 5)
A way of reading with your fingers by feeling little raised dots on paper.
Grade 1 Life Science: Animal Homes and Habits, Lesson 8.4 (grade 1) · Grade 5 Life Science: The Human Body, Lesson 7.4 (grade 5)
brainEnglish
The part inside your skull that gets the messages from your senses and tells you what they mean.
Kindergarten Life Science: God Made the Animals, Lesson 6.3 (grade K)
The part inside your skull that gets the messages from your senses and tells you what they mean.
Kindergarten Life Science: God Made the Animals, Lesson 6.3 (grade K)
brain stemEnglish
The stalk at the base of the brain that joins it to the spinal cord. It runs breathing, heartbeat and other life-keeping jobs automatically.
Grade 5 Life Science: The Human Body, Lesson 6.2 (grade 5)
The stalk at the base of the brain that joins it to the spinal cord. It runs breathing, heartbeat and other life-keeping jobs automatically.
Grade 5 Life Science: The Human Body, Lesson 6.2 (grade 5)
breastplateEnglish
The square, folded pouch of woven cloth that Israel’s high priest wore over his heart, set with twelve precious stones (Exodus 28:15–21).
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.1 (grade 3)
The square, folded pouch of woven cloth that Israel’s high priest wore over his heart, set with twelve precious stones (Exodus 28:15–21).
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.1 (grade 3)
breathingEnglish
Moving air into and out of the lungs (or water over gills). It delivers oxygen to the body and removes carbon dioxide, but it is not the same as cellular respiration.
Grade 7 Life Science: Cells and Microbes, Lesson 5.3 (grade 7)
Moving air into and out of the lungs (or water over gills). It delivers oxygen to the body and removes carbon dioxide, but it is not the same as cellular respiration.
Grade 7 Life Science: Cells and Microbes, Lesson 5.3 (grade 7)
breathing rateEnglish
The number of breaths a person takes in one minute.
Grade 5 Life Science: The Human Body, Lesson 4.3 (grade 5)
The number of breaths a person takes in one minute.
Grade 5 Life Science: The Human Body, Lesson 4.3 (grade 5)
breeding groundsEnglish
The place where a migrating animal mates, builds a nest or den and raises its young.
Grade 6 Life Science: Animal Design and Behavior, Lesson 2.1 (grade 6)
The place where a migrating animal mates, builds a nest or den and raises its young.
Grade 6 Life Science: Animal Design and Behavior, Lesson 2.1 (grade 6)
breeding pairEnglish
The mother and father wolf of a pack, the only wolves in most packs that have pups. Older books called them the “alpha” wolves.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.2 (grade 6)
The mother and father wolf of a pack, the only wolves in most packs that have pups. Older books called them the “alpha” wolves.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.2 (grade 6)
breezeEnglish
A gentle wind that makes leaves rustle and small twigs wiggle.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.3 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.2 (grade K)
A gentle wind that makes leaves rustle and small twigs wiggle.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.3 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.2 (grade K)
brickEnglish
A block made of clay mud, dried hard, used to build walls and houses.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.3 (grade K) · Grade 1 Engineering & Physics, Lesson 3.1 (grade 1) · Kindergarten Engineering & Physics, Lesson 3.1 (grade K) · +1 more
A block made of clay mud, dried hard, used to build walls and houses.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.3 (grade K) · Grade 1 Engineering & Physics, Lesson 3.1 (grade 1) · Kindergarten Engineering & Physics, Lesson 3.1 (grade K) · +1 more
Bridgewater TreatiseEnglish
One of a series of books, funded by the Earl of Bridgewater’s will, written in the 1830s to show the wisdom of God in creation; Buckland wrote the one on geology in 1836.
High School Geology, Lesson 8.4 (grade 9–12)
One of a series of books, funded by the Earl of Bridgewater’s will, written in the 1830s to show the wisdom of God in creation; Buckland wrote the one on geology in 1836.
High School Geology, Lesson 8.4 (grade 9–12)
brittleEnglish
Breaking into pieces when stressed, like glass or cold chalk. Brittle rock makes faults and cracks.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.2 (grade 6) · Grade 4 Engineering & Physics, Lesson 3.1 (grade 4)
Breaking into pieces when stressed, like glass or cold chalk. Brittle rock makes faults and cracks.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.2 (grade 6) · Grade 4 Engineering & Physics, Lesson 3.1 (grade 4)
bronchiEnglish
The two large branches of the windpipe, one going to each lung. They divide again and again into smaller tubes called bronchioles.
Grade 5 Life Science: The Human Body, Lesson 4.1 (grade 5)
The two large branches of the windpipe, one going to each lung. They divide again and again into smaller tubes called bronchioles.
Grade 5 Life Science: The Human Body, Lesson 4.1 (grade 5)
broodingEnglish
Sitting on a clutch of eggs to warm or shelter them, as birds do. Several oviraptorid skeletons were found in this posture over their eggs.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.2 (grade 7) · Explore Animals · Expert, Stop 4.2 (Ages 14+) · Explore Dinosaurs · Expert, Stop 3.2 (Ages 14+) · +1 more
Sitting on a clutch of eggs to warm or shelter them, as birds do. Several oviraptorid skeletons were found in this posture over their eggs.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.2 (grade 7) · Explore Animals · Expert, Stop 4.2 (Ages 14+) · Explore Dinosaurs · Expert, Stop 3.2 (Ages 14+) · +1 more
brookEnglish
A small stream of running water.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.4 (grade K) · Grade 1 Life Science: Animal Homes and Habits, Lesson 4.4 (grade 1)
A small stream of running water.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.4 (grade K) · Grade 1 Life Science: Animal Homes and Habits, Lesson 4.4 (grade 1)
budEnglish
A tiny, tight bundle on a twig. Inside, folded up small, are new leaves or flowers.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.1 (grade K) · Grade 1 Life Science: Animal Homes and Habits, Lesson 6.1 (grade 1)
A tiny, tight bundle on a twig. Inside, folded up small, are new leaves or flowers.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.1 (grade K) · Grade 1 Life Science: Animal Homes and Habits, Lesson 6.1 (grade 1)
buddingEnglish
The way yeast reproduces: a small bump grows on the parent cell, receives a copy of the nucleus, and pinches off as a new cell.
Grade 7 Life Science: Cells and Microbes, Lesson 3.3 (grade 7)
The way yeast reproduces: a small bump grows on the parent cell, receives a copy of the nucleus, and pinches off as a new cell.
Grade 7 Life Science: Cells and Microbes, Lesson 3.3 (grade 7)
bullEnglish
An adult male elephant. Young males leave their family when they are about 12 to 15 years old and live on their own or in loose groups of males.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.3 (grade 6)
An adult male elephant. Young males leave their family when they are about 12 to 15 years old and live on their own or in loose groups of males.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.3 (grade 6)
buoyancyEnglish
The upward push of water on an object. Buoyancy can lift and float away a house that is not anchored down.
Grade 4 Earth Science: Weather and Water, Lesson 6.4 (grade 4) · Grade 7 Earth Science: Earth History and the Flood, Lesson 4.2 (grade 7) · Grade 1 Engineering & Physics, Lesson 6.1 (grade 1) · +3 more
The upward push of water on an object. Buoyancy can lift and float away a house that is not anchored down.
Grade 4 Earth Science: Weather and Water, Lesson 6.4 (grade 4) · Grade 7 Earth Science: Earth History and the Flood, Lesson 4.2 (grade 7) · Grade 1 Engineering & Physics, Lesson 6.1 (grade 1) · +3 more
Burgess ShaleEnglish
A layer of fine, dark shale high in the Canadian Rockies of British Columbia, found by Charles Walcott in 1909, famous for animals preserved with their soft parts.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.1 (grade 8)
A layer of fine, dark shale high in the Canadian Rockies of British Columbia, found by Charles Walcott in 1909, famous for animals preserved with their soft parts.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.1 (grade 8)
buryEnglish
To dig a little hole, put something in it and cover it up with dirt.
Grade 1 Life Science: Animal Homes and Habits, Lesson 1.1 (grade 1)
To dig a little hole, put something in it and cover it up with dirt.
Grade 1 Life Science: Animal Homes and Habits, Lesson 1.1 (grade 1)
butterflyEnglish
The grown-up insect with four big wings covered in tiny scales.
Kindergarten Life Science: God Made the Animals, Lesson 4.2 (grade K)
The grown-up insect with four big wings covered in tiny scales.
Kindergarten Life Science: God Made the Animals, Lesson 4.2 (grade K)
Buys Ballot’s lawEnglish
In the Northern Hemisphere, if you stand with your back to the wind, the low pressure is on your left.
Grade 4 Earth Science: Weather and Water, Lesson 2.4 (grade 4)
In the Northern Hemisphere, if you stand with your back to the wind, the low pressure is on your left.
Grade 4 Earth Science: Weather and Water, Lesson 2.4 (grade 4)
C
cable-tool drillingEnglish
Drilling by lifting a heavy iron bit on a cable and dropping it again and again to pound a hole into rock, then scooping out the chips.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.1 (grade 8)
Drilling by lifting a heavy iron bit on a cable and dropping it again and again to pound a hole into rock, then scooping out the chips.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.1 (grade 8)
calciteEnglish
A soft mineral (3 on the Mohs scale) that fizzes when a drop of acid, such as vinegar, touches it.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.2 (grade 3)
A soft mineral (3 on the Mohs scale) that fizzes when a drop of acid, such as vinegar, touches it.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.2 (grade 3)
calderaEnglish
A large bowl-shaped hollow left when a volcano collapses into the emptied magma chamber beneath it.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.2 (grade 6) · Explore Travel and Faraway Places · Expert, Stop 4.8 (Ages 14+) · Explore Travel and Faraway Places · Ranger, Stop 4.8 (Ages 10–13) · +1 more
A large bowl-shaped hollow left when a volcano collapses into the emptied magma chamber beneath it.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.2 (grade 6) · Explore Travel and Faraway Places · Expert, Stop 4.8 (Ages 14+) · Explore Travel and Faraway Places · Ranger, Stop 4.8 (Ages 10–13) · +1 more
calendar driftEnglish
The slow slipping of calendar dates away from the real seasons when a calendar’s average year is a little too long or too short.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.3 (grade 5)
The slow slipping of calendar dates away from the real seasons when a calendar’s average year is a little too long or too short.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.3 (grade 5)
calibrated paceEnglish
The measured length of your own step, found by counting your paces over a known distance. It lets you measure ground without a tape.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 9.1 (grade 8)
The measured length of your own step, found by counting your paces over a known distance. It lets you measure ground without a tape.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 9.1 (grade 8)
calmEnglish
No wind at all. Smoke goes straight up and a windsock hangs down.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.1 (grade 1) · Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.3 (grade 1)
No wind at all. Smoke goes straight up and a windsock hangs down.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.1 (grade 1) · Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.3 (grade 1)
calvingEnglish
When big chunks of ice break off the front of a glacier and splash into the water.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.1 (grade 2)
When big chunks of ice break off the front of a glacier and splash into the water.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.1 (grade 2)
Cambrian explosionEnglish
A museum word for the sudden appearance of most major animal body plans in the lowest fossil-rich layers, with no chain of ancestors beneath them.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.4 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.1 (grade 8)
A museum word for the sudden appearance of most major animal body plans in the lowest fossil-rich layers, with no chain of ancestors beneath them.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.4 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.1 (grade 8)
canineEnglish
A pointed tooth beside the incisors used for piercing and holding.
Grade 4 Life Science: Classification, Lesson 5.1 (grade 4)
A pointed tooth beside the incisors used for piercing and holding.
Grade 4 Life Science: Classification, Lesson 5.1 (grade 4)
canopyEnglish
The thick upper layer of leaves and branches in a forest, like a green roof. In a rainforest, most animals live there.
Grade 4 Earth Science: Weather and Water, Lesson 8.3 (grade 4) · Grade 1 Engineering & Physics, Lesson 7.2 (grade 1) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 6.1 (grade 6) · +1 more
The thick upper layer of leaves and branches in a forest, like a green roof. In a rainforest, most animals live there.
Grade 4 Earth Science: Weather and Water, Lesson 8.3 (grade 4) · Grade 1 Engineering & Physics, Lesson 7.2 (grade 1) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 6.1 (grade 6) · +1 more
canyonEnglish
A deep valley with steep, rocky sides. Most canyons have a river at the bottom.
Grade 2 Earth Science: The Earth's Surface, Lesson 8.1 (grade 2) · Explore Travel and Faraway Places · Ranger, Stop 4.8 (Ages 10–13) · Explore Travel and Faraway Places, Stop 4.8 (Ages 7–9) · +3 more
A deep valley with steep, rocky sides. Most canyons have a river at the bottom.
Grade 2 Earth Science: The Earth's Surface, Lesson 8.1 (grade 2) · Explore Travel and Faraway Places · Ranger, Stop 4.8 (Ages 10–13) · Explore Travel and Faraway Places, Stop 4.8 (Ages 7–9) · +3 more
canyon (gorge)English
A deep, narrow valley with steep rock walls cut by flowing water.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.4 (grade 6)
A deep, narrow valley with steep rock walls cut by flowing water.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.4 (grade 6)
cap rockEnglish
A hard layer of rock lying on top of softer layers. At Niagara the cap is dolostone and the softer layers are shale and sandstone.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.1 (grade 6) · Geography and Commerce: Sea Lanes, Straits and Trade Routes, Lesson 4.4 (grade 9–12) · High School Geology, Lesson 7.3 (grade 9–12)
A hard layer of rock lying on top of softer layers. At Niagara the cap is dolostone and the softer layers are shale and sandstone.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.1 (grade 6) · Geography and Commerce: Sea Lanes, Straits and Trade Routes, Lesson 4.4 (grade 9–12) · High School Geology, Lesson 7.3 (grade 9–12)
capillaryEnglish
The tiniest blood vessel, so narrow that blood cells pass through in single file. Capillaries connect arteries to veins.
Grade 5 Life Science: The Human Body, Lesson 3.1 (grade 5)
The tiniest blood vessel, so narrow that blood cells pass through in single file. Capillaries connect arteries to veins.
Grade 5 Life Science: The Human Body, Lesson 3.1 (grade 5)
captainEnglish
A leader who is in charge of a group of men.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.4 (grade 2)
A leader who is in charge of a group of men.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.4 (grade 2)
capture spiralEnglish
The sticky, stretchy spiral thread laid around the radii that catches flying insects.
Grade 6 Life Science: Animal Design and Behavior, Lesson 5.2 (grade 6)
The sticky, stretchy spiral thread laid around the radii that catches flying insects.
Grade 6 Life Science: Animal Design and Behavior, Lesson 5.2 (grade 6)
caratEnglish
A unit for weighing gems. 5 carats make 1 gram.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.4 (grade 3) · High School Geology, Lesson 7.2 (grade 9–12)
A unit for weighing gems. 5 carats make 1 gram.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.4 (grade 3) · High School Geology, Lesson 7.2 (grade 9–12)
carbolic acidEnglish
A strong-smelling chemical, also called phenol, that Lister used as the first surgical antiseptic. It kills germs but can also burn skin.
Grade 5 Life Science: The Human Body, Lesson 8.3 (grade 5)
A strong-smelling chemical, also called phenol, that Lister used as the first surgical antiseptic. It kills germs but can also burn skin.
Grade 5 Life Science: The Human Body, Lesson 8.3 (grade 5)
carbonEnglish
The main building material of living things. Coal, charcoal and pencil lead are mostly carbon.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.3 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.4 (grade 3)
The main building material of living things. Coal, charcoal and pencil lead are mostly carbon.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.3 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.4 (grade 3)
carbon monoxideEnglish
A poisonous gas in smoke that takes the place of oxygen on red blood cells, so the blood carries less oxygen.
Grade 5 Life Science: The Human Body, Lesson 4.4 (grade 5)
A poisonous gas in smoke that takes the place of oxygen on red blood cells, so the blood carries less oxygen.
Grade 5 Life Science: The Human Body, Lesson 4.4 (grade 5)
carbon-14English
A radioactive isotope of carbon with 6 protons and 8 neutrons. It forms in the upper atmosphere, is taken in by living things, and decays to nitrogen-14 with a half-life of 5,730 years.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.3 (grade 7) · Explore Dinosaurs · Ranger, Stop 4.9 (Ages 10–13)
A radioactive isotope of carbon with 6 protons and 8 neutrons. It forms in the upper atmosphere, is taken in by living things, and decays to nitrogen-14 with a half-life of 5,730 years.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.3 (grade 7) · Explore Dinosaurs · Ranger, Stop 4.9 (Ages 10–13)
careEnglish
Giving an animal what it needs every day, even when you do not feel like it.
Kindergarten Life Science: God Made the Animals, Lesson 2.4 (grade K)
Giving an animal what it needs every day, even when you do not feel like it.
Kindergarten Life Science: God Made the Animals, Lesson 2.4 (grade K)
carveEnglish
To cut or scrape away bit by bit to make a new shape.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.2 (grade 2) · Grade 2 Earth Science: The Earth's Surface, Lesson 8.3 (grade 2)
To cut or scrape away bit by bit to make a new shape.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.2 (grade 2) · Grade 2 Earth Science: The Earth's Surface, Lesson 8.3 (grade 2)
casingEnglish
The steel or plastic pipe set in a drilled hole to keep it from collapsing and to seal out surface water and dirt.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.3 (grade 8) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.2 (grade 8) · Explore Crafts and Making · Expert, Stop 1.6 (Ages 14+) · +3 more
The steel or plastic pipe set in a drilled hole to keep it from collapsing and to seal out surface water and dirt.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.3 (grade 8) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.2 (grade 8) · Explore Crafts and Making · Expert, Stop 1.6 (Ages 14+) · +3 more
castEnglish
A copy made when something fills up a mold and hardens.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.2 (grade 1) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.2 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.3 (grade 3) · +3 more
A copy made when something fills up a mold and hardens.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.2 (grade 1) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.2 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.3 (grade 3) · +3 more
castingsEnglish
Worm droppings. They are little dark crumbs that make soil rich and good for plants.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.2 (grade K) · Grade 1 Gardening & Animals, Lesson 3.2 (grade 1) · Grade 2 Gardening & Animals, Lesson 3.4 (grade 2) · +3 more
Worm droppings. They are little dark crumbs that make soil rich and good for plants.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.2 (grade K) · Grade 1 Gardening & Animals, Lesson 3.2 (grade 1) · Grade 2 Gardening & Animals, Lesson 3.4 (grade 2) · +3 more
catalog numberEnglish
The number a museum gives each specimen, written on the specimen and in the museum’s record book, like your specimen number.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 8.2 (grade 3) · Grade 7 Earth Science: Earth History and the Flood, Lesson 8.1 (grade 7) · Grade 4 Life Science: Classification, Lesson 9.4 (grade 4)
The number a museum gives each specimen, written on the specimen and in the museum’s record book, like your specimen number.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 8.2 (grade 3) · Grade 7 Earth Science: Earth History and the Flood, Lesson 8.1 (grade 7) · Grade 4 Life Science: Classification, Lesson 9.4 (grade 4)
catastrophic plate tectonicsEnglish
A creationist model proposing that the plates moved rapidly, meters per second, during the Flood year, and then slowed to the centimeters per year measured today.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.4 (grade 6)
A creationist model proposing that the plates moved rapidly, meters per second, during the Flood year, and then slowed to the centimeters per year measured today.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.4 (grade 6)
catastrophismEnglish
The idea, held by Cuvier and Buckland, that much of the rock record was made by sudden, violent events far larger than anything seen in ordinary times.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.3 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 4.4 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.1 (grade 8) · +2 more
The idea, held by Cuvier and Buckland, that much of the rock record was made by sudden, violent events far larger than anything seen in ordinary times.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.3 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 4.4 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.1 (grade 8) · +2 more
caterpillar (larva)English
The baby stage of a butterfly. It hatches from an egg, eats leaves and grows and grows.
Grade 2 Life Science: Animal Families, Lesson 8.1 (grade 2)
The baby stage of a butterfly. It hatches from an egg, eats leaves and grows and grows.
Grade 2 Life Science: Animal Families, Lesson 8.1 (grade 2)
causewayEnglish
A raised road or path across water or wet ground.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.4 (grade 3) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 2.4 (grade 3)
A raised road or path across water or wet ground.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.4 (grade 3) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 2.4 (grade 3)
caveEnglish
A hollow space under the ground, big enough for a person to go inside.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.1 (grade 2) · Kindergarten Geography: God Made the Earth: My First Maps, Lesson 3.4 (grade K)
A hollow space under the ground, big enough for a person to go inside.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.1 (grade 2) · Kindergarten Geography: God Made the Earth: My First Maps, Lesson 3.4 (grade K)
cavityEnglish
A hole in a tooth made when acid from germs feeding on sugar dissolves the enamel.
Grade 5 Life Science: The Human Body, Lesson 5.2 (grade 5) · Grade 2 Physical Education & Health, Lesson 2.2 (grade 2)
A hole in a tooth made when acid from germs feeding on sugar dissolves the enamel.
Grade 5 Life Science: The Human Body, Lesson 5.2 (grade 5) · Grade 2 Physical Education & Health, Lesson 2.2 (grade 2)
cedarEnglish
A big, tall tree with a thick, strong trunk. King Solomon built God’s temple with cedar wood.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 7.4 (grade K) · Explore Dinosaurs · Ranger, Stop 4.2 (Ages 10–13) · Explore Dinosaurs, Stop 4.2 (Ages 7–9) · +1 more
A big, tall tree with a thick, strong trunk. King Solomon built God’s temple with cedar wood.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 7.4 (grade K) · Explore Dinosaurs · Ranger, Stop 4.2 (Ages 10–13) · Explore Dinosaurs, Stop 4.2 (Ages 7–9) · +1 more
celestial poleEnglish
The point in the sky right above the earth’s North or South Pole. The stars seem to circle around it as the earth turns.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.1 (grade 5)
The point in the sky right above the earth’s North or South Pole. The stars seem to circle around it as the earth turns.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.1 (grade 5)
cell divisionEnglish
The way one cell splits to become two new cells. It is how the body grows and repairs itself.
Grade 5 Life Science: The Human Body, Lesson 1.4 (grade 5)
The way one cell splits to become two new cells. It is how the body grows and repairs itself.
Grade 5 Life Science: The Human Body, Lesson 1.4 (grade 5)
cell membraneEnglish
The thin, flexible outer edge of a cell that holds it together and lets some things in and out.
Grade 5 Life Science: The Human Body, Lesson 1.2 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 2.2 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.2 (grade 8)
The thin, flexible outer edge of a cell that holds it together and lets some things in and out.
Grade 5 Life Science: The Human Body, Lesson 1.2 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 2.2 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.2 (grade 8)
cell theoryEnglish
The foundation of biology: all living things are made of cells, the cell is the basic unit of life, and every cell comes from another cell.
Grade 5 Life Science: The Human Body, Lesson 1.4 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 2.1 (grade 7)
The foundation of biology: all living things are made of cells, the cell is the basic unit of life, and every cell comes from another cell.
Grade 5 Life Science: The Human Body, Lesson 1.4 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 2.1 (grade 7)
celluloseEnglish
A tough material made of long chains of sugar molecules that forms plant cell walls. Wood, cotton and paper are mostly cellulose.
Grade 7 Life Science: Cells and Microbes, Lesson 2.3 (grade 7) · Textile Science & Clothing Construction, Lesson 1.2 (grade 9–12)
A tough material made of long chains of sugar molecules that forms plant cell walls. Wood, cotton and paper are mostly cellulose.
Grade 7 Life Science: Cells and Microbes, Lesson 2.3 (grade 7) · Textile Science & Clothing Construction, Lesson 1.2 (grade 9–12)
cementationEnglish
The gluing of sediment grains together by minerals that come out of the water between the grains and harden.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.2 (grade 3) · Grade 6 Earth Science: The Dynamic Earth, Lesson 3.4 (grade 6)
The gluing of sediment grains together by minerals that come out of the water between the grains and harden.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.2 (grade 3) · Grade 6 Earth Science: The Dynamic Earth, Lesson 3.4 (grade 6)
centimeterEnglish
A small step on a ruler, about as wide as your little finger. We can measure rain in centimeters.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 4.3 (grade 1)
A small step on a ruler, about as wide as your little finger. We can measure rain in centimeters.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 4.3 (grade 1)
cerebellumEnglish
The “little brain” at the back, below the cerebrum. It helps with balance and smooth, well-timed movement.
Grade 5 Life Science: The Human Body, Lesson 6.2 (grade 5)
The “little brain” at the back, below the cerebrum. It helps with balance and smooth, well-timed movement.
Grade 5 Life Science: The Human Body, Lesson 6.2 (grade 5)
cerebrumEnglish
The largest, wrinkled part of the brain. It handles thinking, speaking, remembering, the senses and the movements you choose to make.
Grade 5 Life Science: The Human Body, Lesson 6.2 (grade 5)
The largest, wrinkled part of the brain. It handles thinking, speaking, remembering, the senses and the movements you choose to make.
Grade 5 Life Science: The Human Body, Lesson 6.2 (grade 5)
chalkEnglish
A soft, white rock made of tiny, tiny shells, too small to see. Chalk for drawing is soft too.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.2 (grade K) · Explore Dinosaurs · Ranger, Stop 5.3 (Ages 10–13) · Grade 3 Life Science: Plants and Animals Together, Lesson 7.2 (grade 3)
A soft, white rock made of tiny, tiny shells, too small to see. Chalk for drawing is soft too.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.2 (grade K) · Explore Dinosaurs · Ranger, Stop 5.3 (Ages 10–13) · Grade 3 Life Science: Plants and Animals Together, Lesson 7.2 (grade 3)
chamberEnglish
A small, closed space, like a room inside a body or a machine.
Grade 3 Life Science: Plants and Animals Together, Lesson 6.4 (grade 3)
A small, closed space, like a room inside a body or a machine.
Grade 3 Life Science: Plants and Animals Together, Lesson 6.4 (grade 3)
chance of rainEnglish
How likely rain is at one spot, given as a percent. A 40 percent chance means about 4 chances in 10.
Grade 4 Earth Science: Weather and Water, Lesson 5.4 (grade 4)
How likely rain is at one spot, given as a percent. A 40 percent chance means about 4 chances in 10.
Grade 4 Earth Science: Weather and Water, Lesson 5.4 (grade 4)
Chargaff’s ruleEnglish
In double-stranded DNA the amount of A equals the amount of T, and the amount of G equals the amount of C. Erwin Chargaff reported it in 1950.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.1 (grade 8)
In double-stranded DNA the amount of A equals the amount of T, and the amount of G equals the amount of C. Erwin Chargaff reported it in 1950.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.1 (grade 8)
chemical digestionEnglish
Breaking food down with digestive juices that change it into new, simpler substances the body can use.
Grade 5 Life Science: The Human Body, Lesson 5.1 (grade 5)
Breaking food down with digestive juices that change it into new, simpler substances the body can use.
Grade 5 Life Science: The Human Body, Lesson 5.1 (grade 5)
chemical reactionEnglish
A change in which substances mix and turn into new substances, often giving off gas or heat.
Grade 3 Life Science: Plants and Animals Together, Lesson 6.4 (grade 3)
A change in which substances mix and turn into new substances, often giving off gas or heat.
Grade 3 Life Science: Plants and Animals Together, Lesson 6.4 (grade 3)
chernozemEnglish
Russian for “black earth”: the deep, dark, humus-rich grassland soil of the steppe that Dokuchaev studied. The American prairie soils are its cousins.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.2 (grade 8) · Geography and Commerce: Sea Lanes, Straits and Trade Routes, Lesson 4.5 (grade 9–12)
Russian for “black earth”: the deep, dark, humus-rich grassland soil of the steppe that Dokuchaev studied. The American prairie soils are its cousins.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.2 (grade 8) · Geography and Commerce: Sea Lanes, Straits and Trade Routes, Lesson 4.5 (grade 9–12)
chickEnglish
A baby chicken.
Grade 2 Life Science: Animal Families, Lesson 8.2 (grade 2) · Kindergarten Life Science: God Made the Animals, Lesson 1.2 (grade K) · Kindergarten Life Science: God Made the Animals, Lesson 3.2 (grade K)
A baby chicken.
Grade 2 Life Science: Animal Families, Lesson 8.2 (grade 2) · Kindergarten Life Science: God Made the Animals, Lesson 1.2 (grade K) · Kindergarten Life Science: God Made the Animals, Lesson 3.2 (grade K)
childbed feverEnglish
A dangerous infection that some mothers caught soon after giving birth, often carried to them on the unwashed hands of doctors in the 1800s.
Grade 5 Life Science: The Human Body, Lesson 8.4 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 4.1 (grade 7)
A dangerous infection that some mothers caught soon after giving birth, often carried to them on the unwashed hands of doctors in the 1800s.
Grade 5 Life Science: The Human Body, Lesson 8.4 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 4.1 (grade 7)
chitinEnglish
A tough material that makes up fungal cell walls. Insects and crabs use chitin in their outer skeletons too.
Grade 7 Life Science: Cells and Microbes, Lesson 6.1 (grade 7) · Grade 7 Life Science: Cells and Microbes, Lesson 7.3 (grade 7)
A tough material that makes up fungal cell walls. Insects and crabs use chitin in their outer skeletons too.
Grade 7 Life Science: Cells and Microbes, Lesson 6.1 (grade 7) · Grade 7 Life Science: Cells and Microbes, Lesson 7.3 (grade 7)
chromatographyEnglish
A way of separating a mixture by letting a liquid carry it up paper or another material; different substances travel different distances.
Grade 7 Life Science: Cells and Microbes, Lesson 5.4 (grade 7)
A way of separating a mixture by letting a liquid carry it up paper or another material; different substances travel different distances.
Grade 7 Life Science: Cells and Microbes, Lesson 5.4 (grade 7)
chromosomeEnglish
A long DNA molecule wound around proteins. Each kind of living thing has a set number; people have 46 in most body cells.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.2 (grade 8)
A long DNA molecule wound around proteins. Each kind of living thing has a set number; people have 46 in most body cells.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.2 (grade 8)
chronologyEnglish
The ordering of events by date. Genesis 7–8 gives year, month and day for the main events of the Flood.
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.1 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.1 (grade 8)
The ordering of events by date. Genesis 7–8 gives year, month and day for the main events of the Flood.
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.1 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.1 (grade 8)
chrysalis (pupa)English
The hard case a caterpillar makes around itself. Inside, its body changes into a butterfly.
Grade 2 Life Science: Animal Families, Lesson 8.1 (grade 2)
The hard case a caterpillar makes around itself. Inside, its body changes into a butterfly.
Grade 2 Life Science: Animal Families, Lesson 8.1 (grade 2)
ciliaEnglish
Tiny hairlike parts on the cells lining the airways. They beat back and forth together, sweeping mucus up and out of the lungs toward the throat.
Grade 5 Life Science: The Human Body, Lesson 4.4 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 1.4 (grade 7) · Grade 7 Life Science: Cells and Microbes, Lesson 3.2 (grade 7)
Tiny hairlike parts on the cells lining the airways. They beat back and forth together, sweeping mucus up and out of the lungs toward the throat.
Grade 5 Life Science: The Human Body, Lesson 4.4 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 1.4 (grade 7) · Grade 7 Life Science: Cells and Microbes, Lesson 3.2 (grade 7)
cinder coneEnglish
A small, steep cone of loose cinders piled around a single vent, like Parícutin in Mexico; most are short-lived.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.3 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 3.2 (grade 6)
A small, steep cone of loose cinders piled around a single vent, like Parícutin in Mexico; most are short-lived.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.3 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 3.2 (grade 6)
circannual rhythmEnglish
An inner clock that runs on a cycle of about one year, even if the animal is kept indoors where day length never changes.
Grade 6 Life Science: Animal Design and Behavior, Lesson 2.4 (grade 6)
An inner clock that runs on a cycle of about one year, even if the animal is kept indoors where day length never changes.
Grade 6 Life Science: Animal Design and Behavior, Lesson 2.4 (grade 6)
circumferenceEnglish
The distance all the way around a circle or sphere. The earth’s circumference is about 40,000 km (about 24,900 miles).
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.1 (grade 5) · Sports & Games of the World, Lesson 5.4 (grade 8–12) · Geometry, Lesson 11.4 (grade 9–10) · +2 more
The distance all the way around a circle or sphere. The earth’s circumference is about 40,000 km (about 24,900 miles).
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.1 (grade 5) · Sports & Games of the World, Lesson 5.4 (grade 8–12) · Geometry, Lesson 11.4 (grade 9–10) · +2 more
circumpolar starEnglish
A star close enough to the celestial pole that it circles around it without ever setting below the horizon.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.1 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.2 (grade 5)
A star close enough to the celestial pole that it circles around it without ever setting below the horizon.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.1 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.2 (grade 5)
cirrusEnglish
A thin, wispy cloud high in the sky, like a feather or a curl of hair. The name means “curl of hair.”
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 4.1 (grade 1) · Grade 4 Earth Science: Weather and Water, Lesson 3.1 (grade 4) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.3 (grade K)
A thin, wispy cloud high in the sky, like a feather or a curl of hair. The name means “curl of hair.”
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 4.1 (grade 1) · Grade 4 Earth Science: Weather and Water, Lesson 3.1 (grade 4) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.3 (grade K)
cisternEnglish
A lined, waterproof pit or tank that stores rainwater collected from roofs or courtyards. It holds only what is poured in.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.1 (grade 8)
A lined, waterproof pit or tank that stores rainwater collected from roofs or courtyards. It holds only what is poured in.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.1 (grade 8)
claim, evidence, reasoningEnglish
A way to build a paragraph: state the claim, give the evidence that supports it, and explain the reasoning that links the evidence to the claim.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.4 (grade 8)
A way to build a paragraph: state the claim, give the evidence that supports it, and explain the reasoning that links the evidence to the claim.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.4 (grade 8)
classificationEnglish
Sorting living things into groups by shared features, from large groups such as kingdom and class down to genus and species.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.1 (grade 7) · Explore Dinosaurs · Ranger, Stop 2.4 (Ages 10–13) · Grade 5 Gardening & Animals, Lesson 2.1 (grade 5)
Sorting living things into groups by shared features, from large groups such as kingdom and class down to genus and species.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.1 (grade 7) · Explore Dinosaurs · Ranger, Stop 2.4 (Ages 10–13) · Grade 5 Gardening & Animals, Lesson 2.1 (grade 5)
classifyEnglish
To sort things into groups by what they have in common.
Grade 2 Life Science: Animal Families, Lesson 7.1 (grade 2) · Grade 4 Life Science: Classification, Lesson 1.1 (grade 4) · Grade 4 Life Science: Classification, Lesson 2.4 (grade 4)
To sort things into groups by what they have in common.
Grade 2 Life Science: Animal Families, Lesson 7.1 (grade 2) · Grade 4 Life Science: Classification, Lesson 1.1 (grade 4) · Grade 4 Life Science: Classification, Lesson 2.4 (grade 4)
clasticEnglish
Sedimentary rock made of broken pieces of older rock, classified by grain size; conglomerate, sandstone, siltstone, and shale.
High School Geology, Lesson 1.3 (grade 9–12)
Sedimentary rock made of broken pieces of older rock, classified by grain size; conglomerate, sandstone, siltstone, and shale.
High School Geology, Lesson 1.3 (grade 9–12)
clawEnglish
A sharp, curved nail on a foot or hand, for gripping.
Kindergarten Life Science: God Made the Animals, Lesson 7.3 (grade K)
A sharp, curved nail on a foot or hand, for gripping.
Kindergarten Life Science: God Made the Animals, Lesson 7.3 (grade K)
clawsEnglish
A cat’s sharp curved nails. A cat can pull them in or push them out.
Kindergarten Life Science: God Made the Animals, Lesson 2.2 (grade K)
A cat’s sharp curved nails. A cat can pull them in or push them out.
Kindergarten Life Science: God Made the Animals, Lesson 2.2 (grade K)
cleavageEnglish
The way some minerals break along flat, smooth surfaces, always in the same directions. Mica splits into sheets; calcite breaks into slanted boxes.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.4 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.3 (grade 3) · Shop & Trades, Lesson 2.5 (grade 9–12) · +1 more
The way some minerals break along flat, smooth surfaces, always in the same directions. Mica splits into sheets; calcite breaks into slanted boxes.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.4 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.3 (grade 3) · Shop & Trades, Lesson 2.5 (grade 9–12) · +1 more
clickEnglish
A very short, sharp burst of sound a dolphin uses for echolocation. Each click lasts far less than a thousandth of a second.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.2 (grade 6)
A very short, sharp burst of sound a dolphin uses for echolocation. Each click lasts far less than a thousandth of a second.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.2 (grade 6)
cliffEnglish
A tall, steep wall of rock or earth, often beside the sea.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 1.1 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 8.4 (grade 2) · Explore Great Battles, Stop 3.3 (Ages 7–9) · +2 more
A tall, steep wall of rock or earth, often beside the sea.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 1.1 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 8.4 (grade 2) · Explore Great Battles, Stop 3.3 (Ages 7–9) · +2 more
climateEnglish
The usual pattern of weather in a place over many years: how warm or cold, wet or dry it tends to be in each season.
Grade 4 Earth Science: Weather and Water, Lesson 8.1 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 8.4 (grade 4) · Grade 7 Gardening & Animals, Lesson 1.1 (grade 7) · +2 more
The usual pattern of weather in a place over many years: how warm or cold, wet or dry it tends to be in each season.
Grade 4 Earth Science: Weather and Water, Lesson 8.1 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 8.4 (grade 4) · Grade 7 Gardening & Animals, Lesson 1.1 (grade 7) · +2 more
climate normalEnglish
A 30-year average of a weather measurement, such as the average July high temperature or the average January precipitation, for one weather station.
Grade 4 Earth Science: Weather and Water, Lesson 8.4 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 5.1 (grade 6)
A 30-year average of a weather measurement, such as the average July high temperature or the average January precipitation, for one weather station.
Grade 4 Earth Science: Weather and Water, Lesson 8.4 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 5.1 (grade 6)
clitellumEnglish
The thick, smooth band nearer the front end of an adult earthworm (about segments 32 to 37 in the common nightcrawler) that makes the cocoon in which eggs develop.
Grade 7 Life Science: Cells and Microbes, Lesson 8.1 (grade 7)
The thick, smooth band nearer the front end of an adult earthworm (about segments 32 to 37 in the common nightcrawler) that makes the cocoon in which eggs develop.
Grade 7 Life Science: Cells and Microbes, Lesson 8.1 (grade 7)
cloacaEnglish
A shared chamber at the end of the frog’s gut into which the digestive, urinary and reproductive systems all empty before leaving the body.
Grade 7 Life Science: Cells and Microbes, Lesson 8.2 (grade 7)
A shared chamber at the end of the frog’s gut into which the digestive, urinary and reproductive systems all empty before leaving the body.
Grade 7 Life Science: Cells and Microbes, Lesson 8.2 (grade 7)
closed circulatory systemEnglish
A system in which blood always stays inside blood vessels as it travels through the body, as in earthworms and people.
Grade 7 Life Science: Cells and Microbes, Lesson 8.1 (grade 7)
A system in which blood always stays inside blood vessels as it travels through the body, as in earthworms and people.
Grade 7 Life Science: Cells and Microbes, Lesson 8.1 (grade 7)
closed systemEnglish
The assumption that no parent or daughter atoms entered or left the rock after it formed.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.2 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.3 (grade 8) · Explore Dinosaurs · Expert, Stop 4.9 (Ages 14+) · +1 more
The assumption that no parent or daughter atoms entered or left the rock after it formed.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.2 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.3 (grade 8) · Explore Dinosaurs · Expert, Stop 4.9 (Ages 14+) · +1 more
cloudEnglish
Many, many tiny drops of water (or tiny bits of ice) floating together high in the air.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 4.1 (grade 1) · Grade 4 Earth Science: Weather and Water, Lesson 3.1 (grade 4) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.1 (grade K) · +3 more
Many, many tiny drops of water (or tiny bits of ice) floating together high in the air.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 4.1 (grade 1) · Grade 4 Earth Science: Weather and Water, Lesson 3.1 (grade 4) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.1 (grade K) · +3 more
cloud coverEnglish
How much of the sky is hidden by clouds.
Grade 4 Earth Science: Weather and Water, Lesson 3.4 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 9.2 (grade 4)
How much of the sky is hidden by clouds.
Grade 4 Earth Science: Weather and Water, Lesson 3.4 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 9.2 (grade 4)
clutchEnglish
The set of eggs laid in one nest by one mother at one time.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.2 (grade 7) · Explore Animals · Ranger, Stop 2.5 (Ages 10–13) · Explore Animals · Ranger, Stop 2.8 (Ages 10–13) · +3 more
The set of eggs laid in one nest by one mother at one time.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.2 (grade 7) · Explore Animals · Ranger, Stop 2.5 (Ages 10–13) · Explore Animals · Ranger, Stop 2.8 (Ages 10–13) · +3 more
coalEnglish
A black or brown sedimentary rock made mostly of carbon from plants that were buried, squeezed and warmed. It burns.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.3 (grade 3) · Grade 7 Earth Science: Earth History and the Flood, Lesson 2.4 (grade 7)
A black or brown sedimentary rock made mostly of carbon from plants that were buried, squeezed and warmed. It burns.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.3 (grade 3) · Grade 7 Earth Science: Earth History and the Flood, Lesson 2.4 (grade 7)
coal dust explosionEnglish
A blast caused when fine coal dust hanging in the air is ignited, often by a methane explosion. Mines spread powdered limestone (rock dust) so the dust on the floor and walls will not burn.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.3 (grade 8)
A blast caused when fine coal dust hanging in the air is ignited, often by a methane explosion. Mines spread powdered limestone (rock dust) so the dust on the floor and walls will not burn.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.3 (grade 8)
coal rankEnglish
The stage of coal: lignite, subbituminous, bituminous or anthracite, in order of increasing carbon content and hardness.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.4 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.4 (grade 8)
The stage of coal: lignite, subbituminous, bituminous or anthracite, in order of increasing carbon content and hardness.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.4 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.4 (grade 8)
coal seamEnglish
A layer of coal in the rock, made from squeezed and buried plants.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.4 (grade 3)
A layer of coal in the rock, made from squeezed and buried plants.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.4 (grade 3)
cobbleEnglish
A rock about the size of a tennis ball up to a basketball. You need two hands to hold a big one.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 1.3 (grade 1)
A rock about the size of a tennis ball up to a basketball. You need two hands to hold a big one.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 1.3 (grade 1)
cochleaEnglish
The snail-shaped, fluid-filled tube of the inner ear, lined with hair cells that turn vibrations into nerve signals.
Grade 5 Life Science: The Human Body, Lesson 7.2 (grade 5)
The snail-shaped, fluid-filled tube of the inner ear, lined with hair cells that turn vibrations into nerve signals.
Grade 5 Life Science: The Human Body, Lesson 7.2 (grade 5)
codonEnglish
A group of three bases in mRNA that stands for one amino acid or for “stop.” There are 64 codons.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.3 (grade 8)
A group of three bases in mRNA that stands for one amino acid or for “stop.” There are 64 codons.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.3 (grade 8)
coelacanthEnglish
A large, deep-water fish with fleshy, limb-like fins and a three-lobed tail, known from fossils long before a living one was caught in 1938. The name means “hollow spine.”
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.3 (grade 7)
A large, deep-water fish with fleshy, limb-like fins and a three-lobed tail, known from fossils long before a living one was caught in 1938. The name means “hollow spine.”
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.3 (grade 7)
cold currentEnglish
A current that carries cold water from near the poles toward the equator.
Grade 4 Earth Science: Weather and Water, Lesson 7.2 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 7.2 (grade 6)
A current that carries cold water from near the poles toward the equator.
Grade 4 Earth Science: Weather and Water, Lesson 7.2 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 7.2 (grade 6)
cold frontEnglish
A front where cold air pushes in under warmer air and lifts it quickly. Map symbol: a blue line with triangles.
Grade 4 Earth Science: Weather and Water, Lesson 5.3 (grade 4)
A front where cold air pushes in under warmer air and lifts it quickly. Map symbol: a blue line with triangles.
Grade 4 Earth Science: Weather and Water, Lesson 5.3 (grade 4)
collectionEnglish
A group of things you gather and keep with care, such as rocks, shells or leaves.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 1.2 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.1 (grade K) · Grade 1 Life Science: Animal Homes and Habits, Lesson 9.4 (grade 1) · +3 more
A group of things you gather and keep with care, such as rocks, shells or leaves.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 1.2 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.1 (grade K) · Grade 1 Life Science: Animal Homes and Habits, Lesson 9.4 (grade 1) · +3 more
collection labelEnglish
The note on a specimen sheet that tells the plant’s name, the place and habitat where it grew, the date it was collected and the collector’s name.
Grade 4 Life Science: Classification, Lesson 6.4 (grade 4) · Grade 7 Life Science: Cells and Microbes, Lesson 9.4 (grade 7)
The note on a specimen sheet that tells the plant’s name, the place and habitat where it grew, the date it was collected and the collector’s name.
Grade 4 Life Science: Classification, Lesson 6.4 (grade 4) · Grade 7 Life Science: Cells and Microbes, Lesson 9.4 (grade 7)
collectorEnglish
A person who finds things, keeps them with care and learns about them.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 1.1 (grade 1)
A person who finds things, keeps them with care and learns about them.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 1.1 (grade 1)
colonizationEnglish
The arrival and settling of living things on bare new ground.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.4 (grade 6)
The arrival and settling of living things on bare new ground.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.4 (grade 6)
columnar jointingEnglish
The pattern of long five- or six-sided columns produced when a thick body of lava shrinks as it cools.
High School Geology, Lesson 1.2 (grade 9–12)
The pattern of long five- or six-sided columns produced when a thick body of lava shrinks as it cools.
High School Geology, Lesson 1.2 (grade 9–12)
combustionEnglish
Burning: a fast reaction of a fuel with oxygen that gives off heat and light, along with carbon dioxide and water.
Grade 7 Life Science: Cells and Microbes, Lesson 5.3 (grade 7)
Burning: a fast reaction of a fuel with oxygen that gives off heat and light, along with carbon dioxide and water.
Grade 7 Life Science: Cells and Microbes, Lesson 5.3 (grade 7)
comebackEnglish
Growing strong again after almost being lost.
Grade 2 Life Science: Animal Families, Lesson 2.4 (grade 2)
Growing strong again after almost being lost.
Grade 2 Life Science: Animal Families, Lesson 2.4 (grade 2)
cometEnglish
A small, icy body that travels around the Sun. Near the Sun it often shows a fuzzy head and a long glowing tail.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.3 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.4 (grade 5)
A small, icy body that travels around the Sun. Near the Sun it often shows a fuzzy head and a long glowing tail.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.3 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.4 (grade 5)
commandmentEnglish
A rule given by God. God gave Moses the Ten Commandments on Mount Sinai.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.3 (grade 2)
A rule given by God. God gave Moses the Ten Commandments on Mount Sinai.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.3 (grade 2)
common descentEnglish
The claim that different species share ancestors; in its largest form, that all living things descended from one original form.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.2 (grade 8)
The claim that different species share ancestors; in its largest form, that all living things descended from one original form.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.2 (grade 8)
common nameEnglish
The everyday name people use for a living thing, such as “robin” or “candlefish.” It can change from place to place.
Grade 3 Life Science: Plants and Animals Together, Lesson 8.2 (grade 3) · Grade 4 Life Science: Classification, Lesson 1.3 (grade 4)
The everyday name people use for a living thing, such as “robin” or “candlefish.” It can change from place to place.
Grade 3 Life Science: Plants and Animals Together, Lesson 8.2 (grade 3) · Grade 4 Life Science: Classification, Lesson 1.3 (grade 4)
compact boneEnglish
The smooth, dense, heavy outer layer of a bone.
Grade 5 Life Science: The Human Body, Lesson 2.2 (grade 5)
The smooth, dense, heavy outer layer of a bone.
Grade 5 Life Science: The Human Body, Lesson 2.2 (grade 5)
compactionEnglish
The squeezing of buried sediment by the weight of the layers above it, which presses the grains close together and pushes out water.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.2 (grade 3) · Grade 7 Gardening & Animals, Lesson 3.2 (grade 7)
The squeezing of buried sediment by the weight of the layers above it, which presses the grains close together and pushes out water.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.2 (grade 3) · Grade 7 Gardening & Animals, Lesson 3.2 (grade 7)
compassEnglish
A light, balanced magnetized needle that is free to turn and lines up with Earth’s magnetic field.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.3 (grade 6) · Grade 1 Engineering & Physics, Lesson 4.3 (grade 1) · Grade 3 Engineering & Physics, Lesson 4.3 (grade 3) · +3 more
A light, balanced magnetized needle that is free to turn and lines up with Earth’s magnetic field.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.3 (grade 6) · Grade 1 Engineering & Physics, Lesson 4.3 (grade 1) · Grade 3 Engineering & Physics, Lesson 4.3 (grade 3) · +3 more
compass roseEnglish
A drawing that shows the four directions: N for north, E for east, S for south and W for west.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.2 (grade 1) · Explore Travel and Faraway Places · Expert, Stop 1.2 (Ages 14+) · Explore Travel and Faraway Places · Ranger, Stop 1.2 (Ages 10–13) · +3 more
A drawing that shows the four directions: N for north, E for east, S for south and W for west.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.2 (grade 1) · Explore Travel and Faraway Places · Expert, Stop 1.2 (Ages 14+) · Explore Travel and Faraway Places · Ranger, Stop 1.2 (Ages 10–13) · +3 more
compass senseEnglish
The ability to hold a direction, such as “fly south-southwest,” without necessarily knowing where you are.
Grade 6 Life Science: Animal Design and Behavior, Lesson 2.3 (grade 6)
The ability to hold a direction, such as “fly south-southwest,” without necessarily knowing where you are.
Grade 6 Life Science: Animal Design and Behavior, Lesson 2.3 (grade 6)
competenceEnglish
The largest particle a stream can move at a given velocity.
High School Geology, Lesson 3.2 (grade 9–12)
The largest particle a stream can move at a given velocity.
High School Geology, Lesson 3.2 (grade 9–12)
completeEnglish
Having all or nearly all of its parts. Sue is one of the most complete T. rex skeletons ever found.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.2 (grade 3) · Explore Dinosaurs, Stop 2.9 (Ages 7–9)
Having all or nearly all of its parts. Sue is one of the most complete T. rex skeletons ever found.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.2 (grade 3) · Explore Dinosaurs, Stop 2.9 (Ages 7–9)
composite volcano (stratovolcano)English
A tall, steep cone built of alternating layers of lava and tephra, like Mount Fuji or Vesuvius; it often erupts explosively.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.3 (grade 6)
A tall, steep cone built of alternating layers of lava and tephra, like Mount Fuji or Vesuvius; it often erupts explosively.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.3 (grade 6)
compound fractureEnglish
A broken bone that pokes through the skin, leaving an open wound. Today it is often called an open fracture.
Grade 5 Life Science: The Human Body, Lesson 8.3 (grade 5)
A broken bone that pokes through the skin, leaving an open wound. Today it is often called an open fracture.
Grade 5 Life Science: The Human Body, Lesson 8.3 (grade 5)
compound leafEnglish
A leaf whose blade is split into smaller parts called leaflets, all on one petiole, like a clover. A simple leaf has just one blade.
Grade 3 Life Science: Plants and Animals Together, Lesson 1.3 (grade 3)
A leaf whose blade is split into smaller parts called leaflets, all on one petiole, like a clover. A simple leaf has just one blade.
Grade 3 Life Science: Plants and Animals Together, Lesson 1.3 (grade 3)
compound microscopeEnglish
A microscope that uses two sets of lenses, the objective and the eyepiece, so that the second lens magnifies the image made by the first.
Grade 7 Life Science: Cells and Microbes, Lesson 1.2 (grade 7)
A microscope that uses two sets of lenses, the objective and the eyepiece, so that the second lens magnifies the image made by the first.
Grade 7 Life Science: Cells and Microbes, Lesson 1.2 (grade 7)
concordismEnglish
Trying to match the order of events in Genesis 1 to the order claimed by mainstream geology and astronomy, as day-age writers do.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.2 (grade 8)
Trying to match the order of events in Genesis 1 to the order claimed by mainstream geology and astronomy, as day-age writers do.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.2 (grade 8)
cone of depressionEnglish
The funnel-shaped dip in the water table around a pumping well, deepest at the well and fading out with distance.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.3 (grade 8) · High School Geology, Lesson 4.1 (grade 9–12)
The funnel-shaped dip in the water table around a pumping well, deepest at the well and fading out with distance.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.3 (grade 8) · High School Geology, Lesson 4.1 (grade 9–12)
confined aquiferEnglish
An aquifer sandwiched beneath a confining layer of clay or shale, so its water is under pressure and is recharged only where the layer reaches the surface.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.2 (grade 8)
An aquifer sandwiched beneath a confining layer of clay or shale, so its water is under pressure and is recharged only where the layer reaches the surface.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.2 (grade 8)
confining pressureEnglish
The squeeze from all sides that rock feels when it is buried under a great weight of other rock. It helps hold rock together so it bends instead of cracking.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.2 (grade 6)
The squeeze from all sides that rock feels when it is buried under a great weight of other rock. It helps hold rock together so it bends instead of cracking.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.2 (grade 6)
conjunctionEnglish
A time when two planets, or a planet and a star, appear very close together in our sky, even though they are really far apart in space.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.4 (grade 5) · English Grammar, Lesson 7.1 (grade 3–8)
A time when two planets, or a planet and a star, appear very close together in our sky, even though they are really far apart in space.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.4 (grade 5) · English Grammar, Lesson 7.1 (grade 3–8)
constant rateEnglish
The assumption that the half-life has been the same throughout the rock’s history as it is in the lab today.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.2 (grade 7)
The assumption that the half-life has been the same throughout the rock’s history as it is in the lab today.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.2 (grade 7)
constellationEnglish
A pattern of stars that people have named, and the region of sky around it. Astronomers divide the whole sky into 88 constellations.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.2 (grade 5) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 7.3 (grade 8) · Technology Overcoming Geography, Lesson 5.2 (grade 9–12)
A pattern of stars that people have named, and the region of sky around it. Astronomers divide the whole sky into 88 constellations.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.2 (grade 5) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 7.3 (grade 8) · Technology Overcoming Geography, Lesson 5.2 (grade 9–12)
contactEnglish
The surface where one rock layer meets the next.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.2 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.4 (grade 8) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.3 (grade 8) · +1 more
The surface where one rock layer meets the next.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.2 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.4 (grade 8) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.3 (grade 8) · +1 more
contaminationEnglish
Modern carbon that gets into a sample during collection, storage or preparation, which would make an old sample read younger than it is.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.3 (grade 7) · Explore Dinosaurs · Expert, Stop 2.10 (Ages 14+) · Explore Dinosaurs · Expert, Stop 4.9 (Ages 14+) · +2 more
Modern carbon that gets into a sample during collection, storage or preparation, which would make an old sample read younger than it is.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.3 (grade 7) · Explore Dinosaurs · Expert, Stop 2.10 (Ages 14+) · Explore Dinosaurs · Expert, Stop 4.9 (Ages 14+) · +2 more
continental driftEnglish
Wegener’s hypothesis that the continents were once joined in one landmass and have since moved apart.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.1 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 2.2 (grade 6)
Wegener’s hypothesis that the continents were once joined in one landmass and have since moved apart.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.1 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 2.2 (grade 6)
continental shelfEnglish
The gently sloping, shallow sea floor around a continent, covered by seawater but really part of the continent. Its outer edge drops steeply to the deep ocean floor.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.2 (grade 6)
The gently sloping, shallow sea floor around a continent, covered by seawater but really part of the continent. Its outer edge drops steeply to the deep ocean floor.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.2 (grade 6)
contourEnglish
A line that follows one elevation around a hill, staying level. Contour plowing runs the furrows along these lines, across the slope rather than up and down it.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.3 (grade 8)
A line that follows one elevation around a hill, staying level. Contour plowing runs the furrows along these lines, across the slope rather than up and down it.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.3 (grade 8)
contour intervalEnglish
The difference in elevation between one contour line and the next, such as 10 m or 20 m, printed in the map margin.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.2 (grade 8) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 1.1 (grade 6) · High School Geology, Lesson 8.1 (grade 9–12)
The difference in elevation between one contour line and the next, such as 10 m or 20 m, printed in the map margin.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.2 (grade 8) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 1.1 (grade 6) · High School Geology, Lesson 8.1 (grade 9–12)
contractile vacuoleEnglish
A small sac that collects extra water that has seeped into a freshwater protist and squeezes it out, so the cell does not burst.
Grade 7 Life Science: Cells and Microbes, Lesson 3.2 (grade 7)
A small sac that collects extra water that has seeped into a freshwater protist and squeezes it out, so the cell does not burst.
Grade 7 Life Science: Cells and Microbes, Lesson 3.2 (grade 7)
contrivanceEnglish
Paley’s word for an arrangement of parts made to do a job, such as the spring, wheels and hands of a watch.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.1 (grade 8)
Paley’s word for an arrangement of parts made to do a job, such as the spring, wheels and hands of a watch.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.1 (grade 8)
control groupEnglish
The part of an experiment that does not get the change being tested, so the results can be compared with it.
Grade 7 Life Science: Cells and Microbes, Lesson 4.1 (grade 7) · Grade 7 Life Science: Cells and Microbes, Lesson 5.2 (grade 7) · Statistics, Lesson 5.5 (grade 11–12)
The part of an experiment that does not get the change being tested, so the results can be compared with it.
Grade 7 Life Science: Cells and Microbes, Lesson 4.1 (grade 7) · Grade 7 Life Science: Cells and Microbes, Lesson 5.2 (grade 7) · Statistics, Lesson 5.5 (grade 11–12)
controlled experimentEnglish
A test in which one factor (the independent variable) is changed on purpose while everything else is held the same, so that any change in the result can be traced to that one factor.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.3 (grade 7)
A test in which one factor (the independent variable) is changed on purpose while everything else is held the same, so that any change in the result can be traced to that one factor.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.3 (grade 7)
convergent boundaryEnglish
A boundary where two plates move toward each other, making trenches, volcanoes and mountain ranges.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.3 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 5.3 (grade 6)
A boundary where two plates move toward each other, making trenches, volcanoes and mountain ranges.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.3 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 5.3 (grade 6)
convex lensEnglish
A lens that is thicker in the middle than at the edges. It bends light rays together toward a point.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.1 (grade 5)
A lens that is thicker in the middle than at the edges. It bends light rays together toward a point.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.1 (grade 5)
cooling rateEnglish
How fast something cools down. Slow cooling makes big crystals; fast cooling makes small ones.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.3 (grade 3)
How fast something cools down. Slow cooling makes big crystals; fast cooling makes small ones.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.3 (grade 3)
Cooperative ObserverEnglish
A volunteer who reads a thermometer and rain gauge at the same time every day for the National Weather Service. The program began in 1890 and has about 8,700 observers today.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.4 (grade 8)
A volunteer who reads a thermometer and rain gauge at the same time every day for the National Weather Service. The program began in 1890 and has about 8,700 observers today.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.4 (grade 8)
co-optionEnglish
The idea that a part that once did one job could be borrowed and combined with other parts to do a new job.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.3 (grade 8)
The idea that a part that once did one job could be borrowed and combined with other parts to do a new job.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.3 (grade 8)
coordinate reference system (CRS)English
The agreed rule for turning a spot on the round earth into numbers on a flat map, such as latitude and longitude on WGS 84, the system GPS uses.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.3 (grade 8)
The agreed rule for turning a spot on the round earth into numbers on a flat map, such as latitude and longitude on WGS 84, the system GPS uses.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.3 (grade 8)
coquinaEnglish
A rock made of small shells and shell bits stuck together. Its name is a Spanish word for tiny clams.
Grade 2 Earth Science: The Earth's Surface, Lesson 6.3 (grade 2)
A rock made of small shells and shell bits stuck together. Its name is a Spanish word for tiny clams.
Grade 2 Earth Science: The Earth's Surface, Lesson 6.3 (grade 2)
corkEnglish
The light, springy outer bark of the cork oak tree, used for bottle stoppers and corkboards.
Grade 5 Life Science: The Human Body, Lesson 1.1 (grade 5)
The light, springy outer bark of the cork oak tree, used for bottle stoppers and corkboards.
Grade 5 Life Science: The Human Body, Lesson 1.1 (grade 5)
corneaEnglish
The clear, curved window at the front of the eye. It lets light in and does most of the bending of light.
Grade 5 Life Science: The Human Body, Lesson 7.1 (grade 5) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.2 (grade 8)
The clear, curved window at the front of the eye. It lets light in and does most of the bending of light.
Grade 5 Life Science: The Human Body, Lesson 7.1 (grade 5) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.2 (grade 8)
corpus callosumEnglish
A thick bridge of millions of nerve fibers that joins the two hemispheres so they can share messages.
Grade 5 Life Science: The Human Body, Lesson 6.2 (grade 5)
A thick bridge of millions of nerve fibers that joins the two hemispheres so they can share messages.
Grade 5 Life Science: The Human Body, Lesson 6.2 (grade 5)
corundumEnglish
Aluminum oxide, hardness 9; red corundum is ruby, all other colors are sapphire.
High School Geology, Lesson 7.2 (grade 9–12)
Aluminum oxide, hardness 9; red corundum is ruby, all other colors are sapphire.
High School Geology, Lesson 7.2 (grade 9–12)
cosmic raysEnglish
Fast particles from space that strike the upper atmosphere and knock loose neutrons, which turn some nitrogen-14 atoms into carbon-14.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.3 (grade 7)
Fast particles from space that strike the upper atmosphere and knock loose neutrons, which turn some nitrogen-14 atoms into carbon-14.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.3 (grade 7)
couleeEnglish
A steep-walled, dry channel cut into basalt by floodwater. Grand Coulee is about 80 km long.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.1 (grade 6)
A steep-walled, dry channel cut into basalt by floodwater. Grand Coulee is about 80 km long.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.1 (grade 6)
countercurrent exchangeEnglish
An arrangement in which two fluids flow past each other in opposite directions, so that one can pass oxygen (or heat) to the other along the whole length of their contact.
Grade 7 Life Science: Cells and Microbes, Lesson 7.1 (grade 7)
An arrangement in which two fluids flow past each other in opposite directions, so that one can pass oxygen (or heat) to the other along the whole length of their contact.
Grade 7 Life Science: Cells and Microbes, Lesson 7.1 (grade 7)
county seatEnglish
The town where a county’s courthouse and government offices are; the usual home of the county’s land records and engineer’s office.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.1 (grade 8) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 5.2 (grade 4)
The town where a county’s courthouse and government offices are; the usual home of the county’s land records and engineer’s office.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.1 (grade 8) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 5.2 (grade 4)
covenantEnglish
A solemn, binding promise. After the Flood God made a covenant never again to destroy the earth with a flood and set the rainbow as its sign (Genesis 9:11–17).
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.1 (grade 7) · Explore Heroines of History and Faith · Expert, Stop 1.1 (Ages 14+) · Explore Heroines of History and Faith · Ranger, Stop 1.1 (Ages 10–13) · +3 more
A solemn, binding promise. After the Flood God made a covenant never again to destroy the earth with a flood and set the rainbow as its sign (Genesis 9:11–17).
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.1 (grade 7) · Explore Heroines of History and Faith · Expert, Stop 1.1 (Ages 14+) · Explore Heroines of History and Faith · Ranger, Stop 1.1 (Ages 10–13) · +3 more
coverEnglish
Anything that shields the soil surface from rain and wind: grass, leaves, mulch, crop stubble or a growing crop.
Grade 6 Earth Science: The Dynamic Earth, Lesson 9.1 (grade 6)
Anything that shields the soil surface from rain and wind: grass, leaves, mulch, crop stubble or a growing crop.
Grade 6 Earth Science: The Dynamic Earth, Lesson 9.1 (grade 6)
coveringEnglish
What an animal has on the outside of its body: fur, feathers, scales or bare skin.
Grade 1 Life Science: Animal Homes and Habits, Lesson 9.3 (grade 1)
What an animal has on the outside of its body: fur, feathers, scales or bare skin.
Grade 1 Life Science: Animal Homes and Habits, Lesson 9.3 (grade 1)
coverslipEnglish
A very thin square of glass or plastic laid over the specimen to flatten it, keep it from drying and protect the objective lens.
Grade 7 Life Science: Cells and Microbes, Lesson 1.3 (grade 7)
A very thin square of glass or plastic laid over the specimen to flatten it, keep it from drying and protect the objective lens.
Grade 7 Life Science: Cells and Microbes, Lesson 1.3 (grade 7)
cowEnglish
A grown-up mother of the cattle family. A cow makes milk for her baby. The father is called a bull.
Kindergarten Life Science: God Made the Animals, Lesson 1.1 (grade K)
A grown-up mother of the cattle family. A cow makes milk for her baby. The father is called a bull.
Kindergarten Life Science: God Made the Animals, Lesson 1.1 (grade K)
cowpoxEnglish
A mild disease of cows that milkmaids could catch on their hands. It is caused by a germ much like the smallpox germ.
Grade 5 Life Science: The Human Body, Lesson 8.1 (grade 5)
A mild disease of cows that milkmaids could catch on their hands. It is caused by a germ much like the smallpox germ.
Grade 5 Life Science: The Human Body, Lesson 8.1 (grade 5)
crackingEnglish
Breaking large hydrocarbon molecules into smaller ones with heat, pressure or catalysts, so that more gasoline can be made from a barrel.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.4 (grade 8)
Breaking large hydrocarbon molecules into smaller ones with heat, pressure or catalysts, so that more gasoline can be made from a barrel.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.4 (grade 8)
craterEnglish
A round, bowl-shaped hole in the ground, made when something hits hard.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.4 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 2.1 (grade 2) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.1 (grade 5) · +1 more
A round, bowl-shaped hole in the ground, made when something hits hard.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.4 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 2.1 (grade 2) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.1 (grade 5) · +1 more
createEnglish
To bring into being. In Genesis 1 the Hebrew word bara (“created”) always has God as the one who acts; it marks three key points: the heaven and the earth (verse 1), the creatures of the sea and air (verse 21) and man (verse 27).
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.1 (grade 8)
To bring into being. In Genesis 1 the Hebrew word bara (“created”) always has God as the one who acts; it marks three key points: the heaven and the earth (verse 1), the creatures of the sea and air (verse 21) and man (verse 27).
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.1 (grade 8)
created kindEnglish
A group of living things made by God to reproduce after its kind (Genesis 1:24–25). Variation happens within a kind; the creation reading expects gaps between kinds.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.4 (grade 7) · Explore Dinosaurs · Expert, Stop 4.4 (Ages 14+)
A group of living things made by God to reproduce after its kind (Genesis 1:24–25). Variation happens within a kind; the creation reading expects gaps between kinds.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.4 (grade 7) · Explore Dinosaurs · Expert, Stop 4.4 (Ages 14+)
creationEnglish
Everything God made: the ground, the sky, the water, the plants, the animals and people.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 8.1 (grade K) · Explore Dinosaurs, Stop 4.1 (Ages 7–9)
Everything God made: the ground, the sky, the water, the plants, the animals and people.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 8.1 (grade K) · Explore Dinosaurs, Stop 4.1 (Ages 7–9)
CreatorEnglish
The One who made everything. God is the Creator of the heaven and the earth.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 8.4 (grade K)
The One who made everything. God is the Creator of the heaven and the earth.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 8.4 (grade K)
creekEnglish
A small natural stream of flowing water, smaller than a river.
Grade 4 Earth Science: Weather and Water, Lesson 9.4 (grade 4)
A small natural stream of flowing water, smaller than a river.
Grade 4 Earth Science: Weather and Water, Lesson 9.4 (grade 4)
creeping thingEnglish
A King James Bible name for animals that move along close to the ground, like lizards and other reptiles.
Grade 2 Earth Science: The Earth's Surface, Lesson 7.4 (grade 2) · Kindergarten Life Science: God Made the Animals, Lesson 8.2 (grade K)
A King James Bible name for animals that move along close to the ground, like lizards and other reptiles.
Grade 2 Earth Science: The Earth's Surface, Lesson 7.4 (grade 2) · Kindergarten Life Science: God Made the Animals, Lesson 8.2 (grade K)
crescentEnglish
A thin, curved moon shape, like a fingernail clipping or a banana.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.1 (grade 1) · Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.4 (grade 1) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.2 (grade 5) · +2 more
A thin, curved moon shape, like a fingernail clipping or a banana.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.1 (grade 1) · Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.4 (grade 1) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.2 (grade 5) · +2 more
crestEnglish
The top of a wave.
Grade 2 Earth Science: The Earth's Surface, Lesson 6.2 (grade 2) · Explore Dinosaurs · Ranger, Stop 1.8 (Ages 10–13) · Explore Dinosaurs, Stop 1.8 (Ages 7–9) · +3 more
The top of a wave.
Grade 2 Earth Science: The Earth's Surface, Lesson 6.2 (grade 2) · Explore Dinosaurs · Ranger, Stop 1.8 (Ages 10–13) · Explore Dinosaurs, Stop 1.8 (Ages 7–9) · +3 more
CretaceousEnglish
A museum word: the name geologists give to a certain set of rock layers worldwide, from the Latin creta, chalk. On signs it comes with a date; the name itself is only a label for the layers.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.1 (grade 7) · Explore Dinosaurs, Stop 1.1 (Ages 7–9) · Explore Dinosaurs, Stop 5.3 (Ages 7–9)
A museum word: the name geologists give to a certain set of rock layers worldwide, from the Latin creta, chalk. On signs it comes with a date; the name itself is only a label for the layers.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.1 (grade 7) · Explore Dinosaurs, Stop 1.1 (Ages 7–9) · Explore Dinosaurs, Stop 5.3 (Ages 7–9)
crinoidEnglish
A sea animal, also called a sea lily, with a long stem made of round pieces stacked like buttons. Its stem pieces are common fossils.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.4 (grade 3) · Grade 6 Earth Science: The Dynamic Earth, Lesson 5.4 (grade 6)
A sea animal, also called a sea lily, with a long stem made of round pieces stacked like buttons. Its stem pieces are common fossils.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.4 (grade 3) · Grade 6 Earth Science: The Dynamic Earth, Lesson 5.4 (grade 6)
crop yieldEnglish
The amount of crop harvested from a given area of land, often given in kilograms or metric tons per hectare.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.3 (grade 8)
The amount of crop harvested from a given area of land, often given in kilograms or metric tons per hectare.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.3 (grade 8)
cross-beddingEnglish
Small sloping layers inside a single bed, formed on the face of a moving dune or sandbar; these slopes are original, not later tilting.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.3 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.4 (grade 8) · High School Geology, Lesson 1.3 (grade 9–12)
Small sloping layers inside a single bed, formed on the face of a moving dune or sandbar; these slopes are original, not later tilting.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.3 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.4 (grade 8) · High School Geology, Lesson 1.3 (grade 9–12)
cross-cutting relationshipsEnglish
The rule that a feature which cuts across a rock (a crack, fault, dike or erosion surface) is younger than the rock it cuts.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.4 (grade 7) · High School Geology, Lesson 5.2 (grade 9–12)
The rule that a feature which cuts across a rock (a crack, fault, dike or erosion surface) is younger than the rock it cuts.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.4 (grade 7) · High School Geology, Lesson 5.2 (grade 9–12)
cross-cutting ruleEnglish
Anything that cuts across rock layers, such as a crack or a dike, is younger than the layers it cuts.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.3 (grade 3)
Anything that cuts across rock layers, such as a crack or a dike, is younger than the layers it cuts.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.3 (grade 3)
cross-sectionEnglish
A drawing of what you would see if you sliced straight down through the ground and looked at the cut side.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.4 (grade 3) · Grade 4 Earth Science: Weather and Water, Lesson 9.4 (grade 4) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.4 (grade 8) · +2 more
A drawing of what you would see if you sliced straight down through the ground and looked at the cut side.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.4 (grade 3) · Grade 4 Earth Science: Weather and Water, Lesson 9.4 (grade 4) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.4 (grade 8) · +2 more
crosswind componentEnglish
The part of the wind blowing across the runway rather than along it, found by multiplying the wind speed by the sine of the angle between the wind and the runway.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.3 (grade 8)
The part of the wind blowing across the runway rather than along it, found by multiplying the wind speed by the sine of the angle between the wind and the runway.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.3 (grade 8)
crustEnglish
Earth’s thin, rocky outer layer: about 5 to 10 km thick under the oceans and about 30 to 70 km thick under the continents.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.2 (grade 6) · Explore Hospitality and Home, Stop 1.7 (Ages 7–9) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 2.1 (grade 6)
Earth’s thin, rocky outer layer: about 5 to 10 km thick under the oceans and about 30 to 70 km thick under the continents.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.2 (grade 6) · Explore Hospitality and Home, Stop 1.7 (Ages 7–9) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 2.1 (grade 6)
crustaceanEnglish
An arthropod with two pairs of antennae and a hard shell, that usually breathes with gills, such as a crab, lobster, shrimp, crayfish or pill bug.
Grade 4 Life Science: Classification, Lesson 3.2 (grade 4)
An arthropod with two pairs of antennae and a hard shell, that usually breathes with gills, such as a crab, lobster, shrimp, crayfish or pill bug.
Grade 4 Life Science: Classification, Lesson 3.2 (grade 4)
crustal thickeningEnglish
The piling up of crust by folding and thrusting, so that it becomes much thicker than normal. Under Tibet the crust is about twice its usual thickness.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.3 (grade 6)
The piling up of crust by folding and thrusting, so that it becomes much thicker than normal. Under Tibet the crust is about twice its usual thickness.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.3 (grade 6)
cubitEnglish
A length from the elbow to the tip of the longest finger. Noah built the ark in cubits.
Grade 2 Earth Science: The Earth's Surface, Lesson 7.4 (grade 2) · Grade 6 Earth Science: The Dynamic Earth, Lesson 7.4 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 4.1 (grade 7) · +3 more
A length from the elbow to the tip of the longest finger. Noah built the ark in cubits.
Grade 2 Earth Science: The Earth's Surface, Lesson 7.4 (grade 2) · Grade 6 Earth Science: The Dynamic Earth, Lesson 7.4 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 4.1 (grade 7) · +3 more
cumulonimbusEnglish
A towering thunderstorm cloud that can bring lightning, heavy rain, hail and strong gusts of wind.
Grade 4 Earth Science: Weather and Water, Lesson 3.2 (grade 4)
A towering thunderstorm cloud that can bring lightning, heavy rain, hail and strong gusts of wind.
Grade 4 Earth Science: Weather and Water, Lesson 3.2 (grade 4)
cuneiformEnglish
Wedge-shaped writing pressed into wet clay with a reed, used in Mesopotamia for about three thousand years.
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.3 (grade 7) · Sports & Games of the World, Lesson 2.1 (grade 4–7) · Sports & Games of the World, Lesson 1.1 (grade 8–12)
Wedge-shaped writing pressed into wet clay with a reed, used in Mesopotamia for about three thousand years.
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.3 (grade 7) · Sports & Games of the World, Lesson 2.1 (grade 4–7) · Sports & Games of the World, Lesson 1.1 (grade 8–12)
currentEnglish
Water moving in one direction, like the water flowing along a creek.
Grade 2 Earth Science: The Earth's Surface, Lesson 9.4 (grade 2) · Grade 2 Engineering & Physics, Lesson 6.4 (grade 2) · Grade 5 Engineering & Physics, Lesson 4.1 (grade 5) · +1 more
Water moving in one direction, like the water flowing along a creek.
Grade 2 Earth Science: The Earth's Surface, Lesson 9.4 (grade 2) · Grade 2 Engineering & Physics, Lesson 6.4 (grade 2) · Grade 5 Engineering & Physics, Lesson 4.1 (grade 5) · +1 more
current alignmentEnglish
The tendency of long objects such as sticks or bones to line up with the flow that moved them. It is a clue that water, not stillness, laid the bed.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.2 (grade 6)
The tendency of long objects such as sticks or bones to line up with the flow that moved them. It is a clue that water, not stillness, laid the bed.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.2 (grade 6)
cytoplasmEnglish
The jelly-like material that fills the cell, where much of the cell’s work is done.
Grade 5 Life Science: The Human Body, Lesson 1.2 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 2.2 (grade 7)
The jelly-like material that fills the cell, where much of the cell’s work is done.
Grade 5 Life Science: The Human Body, Lesson 1.2 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 2.2 (grade 7)
D
daciteEnglish
A pale volcanic rock rich in silica, between andesite and rhyolite, with crystals of feldspar, amphibole and pyroxene set in volcanic glass. The Mount St. Helens dome is made of it.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.4 (grade 7)
A pale volcanic rock rich in silica, between andesite and rhyolite, with crystals of feldspar, amphibole and pyroxene set in volcanic glass. The Mount St. Helens dome is made of it.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.4 (grade 7)
damEnglish
A wall built across a river or stream to hold back water.
Grade 4 Earth Science: Weather and Water, Lesson 6.1 (grade 4) · Grade 2 Engineering & Physics, Lesson 5.3 (grade 2) · Grade 4 Engineering & Physics, Lesson 5.3 (grade 4) · +3 more
A wall built across a river or stream to hold back water.
Grade 4 Earth Science: Weather and Water, Lesson 6.1 (grade 4) · Grade 2 Engineering & Physics, Lesson 5.3 (grade 2) · Grade 4 Engineering & Physics, Lesson 5.3 (grade 4) · +3 more
dark adaptationEnglish
The way your eyes slowly grow more sensitive in the dark, so you see more stars after waiting 20 to 30 minutes.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.1 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.4 (grade 5)
The way your eyes slowly grow more sensitive in the dark, so you see more stars after waiting 20 to 30 minutes.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.1 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.4 (grade 5)
dataEnglish
Facts and measurements that are recorded so they can be compared and studied.
Grade 4 Earth Science: Weather and Water, Lesson 3.4 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 7.1 (grade 4) · Grade 4 Engineering & Physics, Lesson 7.3 (grade 4) · +3 more
Facts and measurements that are recorded so they can be compared and studied.
Grade 4 Earth Science: Weather and Water, Lesson 3.4 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 7.1 (grade 4) · Grade 4 Engineering & Physics, Lesson 7.3 (grade 4) · +3 more
data labelEnglish
The label with a specimen giving at least the name (if known), date, exact place, habitat and collector. Without it, a specimen loses most of its scientific value.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 9.4 (grade 8)
The label with a specimen giving at least the name (if known), date, exact place, habitat and collector. Without it, a specimen loses most of its scientific value.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 9.4 (grade 8)
daughter isotopeEnglish
The isotope produced by the decay, such as lead-206 from uranium-238 or nitrogen-14 from carbon-14.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.1 (grade 7)
The isotope produced by the decay, such as lead-206 from uranium-238 or nitrogen-14 from carbon-14.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.1 (grade 7)
dawn chorusEnglish
The time just after sunrise in spring when many birds sing at once.
Kindergarten Life Science: God Made the Animals, Lesson 3.3 (grade K)
The time just after sunrise in spring when many birds sing at once.
Kindergarten Life Science: God Made the Animals, Lesson 3.3 (grade K)
day-age viewEnglish
The reading of Genesis 1 in which each of the six “days” is a long age of time, so creation took place over a very long period in the order Genesis gives.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.2 (grade 8)
The reading of Genesis 1 in which each of the six “days” is a long age of time, so creation took place over a very long period in the order Genesis gives.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.2 (grade 8)
daylightEnglish
The time from sunrise to sunset, when the sun is up in the sky.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.2 (grade K)
The time from sunrise to sunset, when the sun is up in the sky.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.2 (grade K)
dealerEnglish
A person who buys and sells specimens, such as the owner of a rock shop.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 8.2 (grade 3)
A person who buys and sells specimens, such as the owner of a rock shop.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 8.2 (grade 3)
debris avalancheEnglish
A fast-moving landslide of broken rock, ice and soil; the one at Mount St. Helens in 1980 was the largest in recorded history.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.1 (grade 8)
A fast-moving landslide of broken rock, ice and soil; the one at Mount St. Helens in 1980 was the largest in recorded history.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.1 (grade 8)
debris flowEnglish
A fast, water-soaked flow of mud, rock and plants that rushes down a valley like wet concrete; on a volcano it is called a lahar.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.3 (grade 6)
A fast, water-soaked flow of mud, rock and plants that rushes down a valley like wet concrete; on a volcano it is called a lahar.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.3 (grade 6)
decapodEnglish
A crustacean with ten legs (five pairs), like a crab, lobster, shrimp or crayfish. The name means “ten feet.”
Grade 4 Life Science: Classification, Lesson 3.2 (grade 4)
A crustacean with ten legs (five pairs), like a crab, lobster, shrimp or crayfish. The name means “ten feet.”
Grade 4 Life Science: Classification, Lesson 3.2 (grade 4)
decay curveEnglish
A graph of the amount of parent remaining against time. It drops by half every half-life, steep at first and flatter later.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.1 (grade 7)
A graph of the amount of parent remaining against time. It drops by half every half-life, steep at first and flatter later.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.1 (grade 7)
deciduous treeEnglish
A tree that drops all its leaves in the fall and grows new ones in the spring, like a maple or an oak.
Grade 1 Life Science: Animal Homes and Habits, Lesson 6.1 (grade 1)
A tree that drops all its leaves in the fall and grows new ones in the spring, like a maple or an oak.
Grade 1 Life Science: Animal Homes and Habits, Lesson 6.1 (grade 1)
declinationEnglish
The angle between true (geographic) north and the direction a compass points. It differs from place to place and changes slowly over time.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.3 (grade 6) · Geography and History: Why Borders Fall Where They Do, Lesson 10.1 (grade 9–12)
The angle between true (geographic) north and the direction a compass points. It differs from place to place and changes slowly over time.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.3 (grade 6) · Geography and History: Why Borders Fall Where They Do, Lesson 10.1 (grade 9–12)
deep currentEnglish
A slow current far below the surface, made when cold, salty, dense water sinks and spreads along the ocean floor.
Grade 4 Earth Science: Weather and Water, Lesson 7.3 (grade 4)
A slow current far below the surface, made when cold, salty, dense water sinks and spreads along the ocean floor.
Grade 4 Earth Science: Weather and Water, Lesson 7.3 (grade 4)
deep sleepEnglish
The stage of slowest brain waves, when it is hardest to wake up; breathing and heartbeat slow, and the body does much of its growth and repair.
Grade 5 Life Science: The Human Body, Lesson 6.4 (grade 5)
The stage of slowest brain waves, when it is hardest to wake up; breathing and heartbeat slow, and the body does much of its growth and repair.
Grade 5 Life Science: The Human Body, Lesson 6.4 (grade 5)
deismEnglish
Belief in a Creator who made the world and its laws but does not act within it or reveal himself in Scripture.
High School Geology, Lesson 8.3 (grade 9–12)
Belief in a Creator who made the world and its laws but does not act within it or reveal himself in Scripture.
High School Geology, Lesson 8.3 (grade 9–12)
deltaEnglish
A fan of sediment built where a river slows down and drops its load as it enters a sea or lake. Named by the Greeks for the triangle shape of the letter Δ.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.2 (grade 6) · Explore Travel and Faraway Places · Ranger, Stop 4.6 (Ages 10–13) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 3.3 (grade 3) · +3 more
A fan of sediment built where a river slows down and drops its load as it enters a sea or lake. Named by the Greeks for the triangle shape of the letter Δ.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.2 (grade 6) · Explore Travel and Faraway Places · Ranger, Stop 4.6 (Ages 10–13) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 3.3 (grade 3) · +3 more
denseEnglish
Heavy for its size. Gold is very dense: a small flake weighs much more than a sand grain of the same size.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.3 (grade 3)
Heavy for its size. Gold is very dense: a small flake weighs much more than a sand grain of the same size.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.3 (grade 3)
density altitudeEnglish
The altitude in the standard atmosphere that has the same air density as the air at the airport right now. Hot, high and humid air has a high density altitude, so wings and engines perform as if they were higher up.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.3 (grade 8)
The altitude in the standard atmosphere that has the same air density as the air at the airport right now. Hot, high and humid air has a high density altitude, so wings and engines perform as if they were higher up.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.3 (grade 8)
dentin and pulpEnglish
Dentin is the yellowish, bone-like layer under the enamel. The pulp is the soft center of the tooth, with nerves and blood vessels.
Grade 5 Life Science: The Human Body, Lesson 5.2 (grade 5)
Dentin is the yellowish, bone-like layer under the enamel. The pulp is the soft center of the tooth, with nerves and blood vessels.
Grade 5 Life Science: The Human Body, Lesson 5.2 (grade 5)
depositionEnglish
The laying down of eroded material in a new place when the water, wind or ice that carried it slows down.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.1 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 1.2 (grade 7) · Explore Great Battles · Expert, Stop 3.4 (Ages 14+)
The laying down of eroded material in a new place when the water, wind or ice that carried it slows down.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.1 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 1.2 (grade 7) · Explore Great Battles · Expert, Stop 3.4 (Ages 14+)
dermal denticleEnglish
A tiny tooth-like scale in a shark’s skin, built like a tooth with a hard outer layer, dentine and a pulp cavity. The name means “little skin tooth.”
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.2 (grade 6)
A tiny tooth-like scale in a shark’s skin, built like a tooth with a hard outer layer, dentine and a pulp cavity. The name means “little skin tooth.”
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.2 (grade 6)
descent with modificationEnglish
Darwin’s phrase for the idea that living things change over generations as they descend from their ancestors.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.2 (grade 8)
Darwin’s phrase for the idea that living things change over generations as they descend from their ancestors.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.2 (grade 8)
desertEnglish
A very dry place with little rain, where few plants grow.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.4 (grade 1) · Grade 4 Earth Science: Weather and Water, Lesson 8.3 (grade 4) · Explore Animals, Stop 3.10 (Ages 7–9) · +3 more
A very dry place with little rain, where few plants grow.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.4 (grade 1) · Grade 4 Earth Science: Weather and Water, Lesson 8.3 (grade 4) · Explore Animals, Stop 3.10 (Ages 7–9) · +3 more
design cycleEnglish
The repeating steps engineers use to invent: define the problem, find ideas, build a prototype, test it and improve it.
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.4 (grade 6)
The repeating steps engineers use to invent: define the problem, find ideas, build a prototype, test it and improve it.
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.4 (grade 6)
design inferenceEnglish
Reasoning from the features of an object or event to the conclusion that a mind produced it, as archaeologists do with arrowheads and detectives do with clues.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.3 (grade 8)
Reasoning from the features of an object or event to the conclusion that a mind produced it, as archaeologists do with arrowheads and detectives do with clues.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.3 (grade 8)
detection limitEnglish
The smallest amount an instrument can tell apart from zero. A reading below it is reported as “not detected,” which is not the same as none.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.3 (grade 7)
The smallest amount an instrument can tell apart from zero. A reading below it is reported as “not detected,” which is not the same as none.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.3 (grade 7)
DevonianEnglish
A museum word: the layer set first studied in Devon, England, in which the lowest fossil coelacanths and many fish are found. On a sign it comes with a date of about 400 million years.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.3 (grade 7)
A museum word: the layer set first studied in Devon, England, in which the lowest fossil coelacanths and many fish are found. On a sign it comes with a date of about 400 million years.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.3 (grade 7)
dewEnglish
Drops of water that condense on grass, leaves and other cool surfaces, usually during a clear, calm night.
Grade 4 Earth Science: Weather and Water, Lesson 1.3 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 3.3 (grade 4)
Drops of water that condense on grass, leaves and other cool surfaces, usually during a clear, calm night.
Grade 4 Earth Science: Weather and Water, Lesson 1.3 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 3.3 (grade 4)
dew pointEnglish
The temperature air must cool to before its water vapor begins to condense into drops. The more water vapor in the air, the higher the dew point.
Grade 4 Earth Science: Weather and Water, Lesson 1.3 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 3.3 (grade 4) · Shop & Trades, Lesson 6.1 (grade 9–12)
The temperature air must cool to before its water vapor begins to condense into drops. The more water vapor in the air, the higher the dew point.
Grade 4 Earth Science: Weather and Water, Lesson 1.3 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 3.3 (grade 4) · Shop & Trades, Lesson 6.1 (grade 9–12)
diameterEnglish
The distance straight across a circle or ball through its center.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.2 (grade 5) · Pre-Algebra, Lesson 12.4 (grade 6–8)
The distance straight across a circle or ball through its center.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.2 (grade 5) · Pre-Algebra, Lesson 12.4 (grade 6–8)
diapauseEnglish
A resting state in which an insect’s growth or breeding is paused. Fall monarchs are in a breeding diapause: they do not mate or lay eggs until spring.
Grade 6 Life Science: Animal Design and Behavior, Lesson 2.2 (grade 6)
A resting state in which an insect’s growth or breeding is paused. Fall monarchs are in a breeding diapause: they do not mate or lay eggs until spring.
Grade 6 Life Science: Animal Design and Behavior, Lesson 2.2 (grade 6)
digEnglish
A place where fossil hunters carefully take bones out of the ground.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 7.2 (grade K)
A place where fossil hunters carefully take bones out of the ground.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 7.2 (grade K)
dikeEnglish
A wall-shaped body of igneous rock that formed when melted rock pushed up through a crack and hardened.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.3 (grade 3) · Grade 7 Earth Science: Earth History and the Flood, Lesson 1.4 (grade 7) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 4.2 (grade 3) · +3 more
A wall-shaped body of igneous rock that formed when melted rock pushed up through a crack and hardened.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.3 (grade 3) · Grade 7 Earth Science: Earth History and the Flood, Lesson 1.4 (grade 7) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 4.2 (grade 3) · +3 more
dinosaurEnglish
A land animal God made, now gone, that walked with its legs straight under its body. We know dinosaurs from their bones.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 7.1 (grade K) · Explore Dinosaurs · Expert, Stop 4.1 (Ages 14+) · Explore Dinosaurs · Ranger, Stop 4.1 (Ages 10–13) · +3 more
A land animal God made, now gone, that walked with its legs straight under its body. We know dinosaurs from their bones.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 7.1 (grade K) · Explore Dinosaurs · Expert, Stop 4.1 (Ages 14+) · Explore Dinosaurs · Ranger, Stop 4.1 (Ages 10–13) · +3 more
DinosauriaEnglish
The name Richard Owen gave in 1842 to a group of large fossil reptiles with upright legs. It means “fearfully great lizards.” Today it names all dinosaurs.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.1 (grade 7) · Explore Dinosaurs · Expert, Stop 2.4 (Ages 14+) · Explore Dinosaurs · Ranger, Stop 2.4 (Ages 10–13) · +1 more
The name Richard Owen gave in 1842 to a group of large fossil reptiles with upright legs. It means “fearfully great lizards.” Today it names all dinosaurs.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.1 (grade 7) · Explore Dinosaurs · Expert, Stop 2.4 (Ages 14+) · Explore Dinosaurs · Ranger, Stop 2.4 (Ages 10–13) · +1 more
dioramaEnglish
A small model of a real place, built inside a box, with a painted background and little things in front.
Grade 2 Earth Science: The Earth's Surface, Lesson 8.4 (grade 2) · Explore Dinosaurs · Ranger, Stop 5.10 (Ages 10–13) · Grade 3 Life Science: Plants and Animals Together, Lesson 9.3 (grade 3)
A small model of a real place, built inside a box, with a painted background and little things in front.
Grade 2 Earth Science: The Earth's Surface, Lesson 8.4 (grade 2) · Explore Dinosaurs · Ranger, Stop 5.10 (Ages 10–13) · Grade 3 Life Science: Plants and Animals Together, Lesson 9.3 (grade 3)
DiplodocusEnglish
A very long dinosaur with a long neck, a tiny head and a long whip tail. It ate plants.
Kindergarten Life Science: God Made the Animals, Lesson 7.2 (grade K)
A very long dinosaur with a long neck, a tiny head and a long whip tail. It ate plants.
Kindergarten Life Science: God Made the Animals, Lesson 7.2 (grade K)
dipole fieldEnglish
The main part of Earth’s magnetic field, which acts like one giant bar magnet through the center of the earth. Its strength is called the dipole strength.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.4 (grade 6)
The main part of Earth’s magnetic field, which acts like one giant bar magnet through the center of the earth. Its strength is called the dipole strength.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.4 (grade 6)
direct flight musclesEnglish
Flight muscles attached right to the bases of the wings, which pull each wing up or down. Dragonflies fly this way.
Grade 6 Life Science: Animal Design and Behavior, Lesson 1.3 (grade 6)
Flight muscles attached right to the bases of the wings, which pull each wing up or down. Dragonflies fly this way.
Grade 6 Life Science: Animal Design and Behavior, Lesson 1.3 (grade 6)
direct pressureEnglish
Pressing firmly on a bleeding wound with a clean cloth or gauze to help the blood clot and stop the bleeding.
Grade 5 Life Science: The Human Body, Lesson 8.4 (grade 5)
Pressing firmly on a bleeding wound with a clean cloth or gauze to help the blood clot and stop the bleeding.
Grade 5 Life Science: The Human Body, Lesson 8.4 (grade 5)
direct raysEnglish
Sunlight that strikes the ground nearly straight on, when the Sun is high. Direct rays pack their energy into a small area and warm the ground well.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.1 (grade 5)
Sunlight that strikes the ground nearly straight on, when the Sun is high. Direct rays pack their energy into a small area and warm the ground well.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.1 (grade 5)
disarticulatedEnglish
Bones separated from one another and mixed, which happens when a carcass rots, is scavenged or is tumbled by water before burial.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.2 (grade 6) · Explore Dinosaurs · Expert, Stop 4.5 (Ages 14+)
Bones separated from one another and mixed, which happens when a carcass rots, is scavenged or is tumbled by water before burial.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.2 (grade 6) · Explore Dinosaurs · Expert, Stop 4.5 (Ages 14+)
discEnglish
A tough, springy cushion between two vertebrae that lets the back bend and soaks up bumps.
Grade 4 Life Science: Classification, Lesson 2.2 (grade 4)
A tough, springy cushion between two vertebrae that lets the back bend and soaks up bumps.
Grade 4 Life Science: Classification, Lesson 2.2 (grade 4)
disconformityEnglish
A gap between parallel layers that shows signs of erosion, such as channels, soil or pebbles of the lower rock.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.2 (grade 7)
A gap between parallel layers that shows signs of erosion, such as channels, soil or pebbles of the lower rock.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.2 (grade 7)
discordant datesEnglish
Dates from different minerals or methods on the same rock that disagree by more than their stated errors.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.4 (grade 7)
Dates from different minerals or methods on the same rock that disagree by more than their stated errors.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.4 (grade 7)
disease resistanceEnglish
An inherited ability of a plant or animal to keep from being badly harmed by a particular disease.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.3 (grade 8)
An inherited ability of a plant or animal to keep from being badly harmed by a particular disease.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.3 (grade 8)
dispersalEnglish
When a young animal leaves the group it was born into to find a mate and a home of its own.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.2 (grade 6)
When a young animal leaves the group it was born into to find a mate and a home of its own.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.2 (grade 6)
dispersionEnglish
The scattering of the nations from Babel described in Genesis 11, after which Noah’s descendants spread over the earth.
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.3 (grade 7) · Playing the Odds, Lesson 6.3 (grade 4–7) · Playing the Odds, Lesson 3.5 (grade 8–12)
The scattering of the nations from Babel described in Genesis 11, after which Noah’s descendants spread over the earth.
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.3 (grade 7) · Playing the Odds, Lesson 6.3 (grade 4–7) · Playing the Odds, Lesson 3.5 (grade 8–12)
displacementEnglish
The volume or mass of water a floating vessel pushes aside; a floating ship displaces water equal to its own total weight.
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.2 (grade 7) · Grade 6 Engineering & Physics, Lesson 6.1 (grade 6) · Grade 7 Engineering & Physics, Lesson 1.3 (grade 7) · +3 more
The volume or mass of water a floating vessel pushes aside; a floating ship displaces water equal to its own total weight.
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.2 (grade 7) · Grade 6 Engineering & Physics, Lesson 6.1 (grade 6) · Grade 7 Engineering & Physics, Lesson 1.3 (grade 7) · +3 more
dissectionEnglish
Carefully cutting apart a dead plant or animal body to see and study its parts.
Grade 5 Life Science: The Human Body, Lesson 2.1 (grade 5)
Carefully cutting apart a dead plant or animal body to see and study its parts.
Grade 5 Life Science: The Human Body, Lesson 2.1 (grade 5)
dissolved oxygenEnglish
Oxygen gas mixed into water as single molecules, too small to see. It is measured in milligrams per liter (mg/L). It is not the oxygen atom that is part of each water molecule.
Grade 7 Life Science: Cells and Microbes, Lesson 7.1 (grade 7)
Oxygen gas mixed into water as single molecules, too small to see. It is measured in milligrams per liter (mg/L). It is not the oxygen atom that is part of each water molecule.
Grade 7 Life Science: Cells and Microbes, Lesson 7.1 (grade 7)
distributaryEnglish
A channel that splits off from the main river on a delta and carries part of its water to the sea. The opposite of a tributary, which joins a river.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.2 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 4.3 (grade 6) · Grade 7 Geography: Regions of the World, Lesson 1.4 (grade 7)
A channel that splits off from the main river on a delta and carries part of its water to the sea. The opposite of a tributary, which joins a river.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.2 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 4.3 (grade 6) · Grade 7 Geography: Regions of the World, Lesson 1.4 (grade 7)
diurnalEnglish
Active in the daytime and resting at night, like bees, butterflies and robins.
Grade 3 Life Science: Plants and Animals Together, Lesson 9.2 (grade 3)
Active in the daytime and resting at night, like bees, butterflies and robins.
Grade 3 Life Science: Plants and Animals Together, Lesson 9.2 (grade 3)
dive responseEnglish
The changes in a diving mammal’s body when it goes underwater: the heart slows and blood is sent mainly to the brain and heart, so stored oxygen lasts longer.
Grade 6 Life Science: Animal Design and Behavior, Lesson 7.1 (grade 6)
The changes in a diving mammal’s body when it goes underwater: the heart slows and blood is sent mainly to the brain and heart, so stored oxygen lasts longer.
Grade 6 Life Science: Animal Design and Behavior, Lesson 7.1 (grade 6)
divergent boundaryEnglish
A boundary where two plates move apart. Hot rock rises to fill the gap, making mid-ocean ridges and rift valleys.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.3 (grade 6)
A boundary where two plates move apart. Hot rock rises to fill the gap, making mid-ocean ridges and rift valleys.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.3 (grade 6)
divideEnglish
The high ground, such as a ridge or mountain crest, that separates one watershed from the next.
Grade 4 Earth Science: Weather and Water, Lesson 6.3 (grade 4)
The high ground, such as a ridge or mountain crest, that separates one watershed from the next.
Grade 4 Earth Science: Weather and Water, Lesson 6.3 (grade 4)
DNA (deoxyribonucleic acid)English
The long molecule in every living cell that carries the hereditary instructions passed from parents to offspring.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.1 (grade 8)
The long molecule in every living cell that carries the hereditary instructions passed from parents to offspring.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.1 (grade 8)
docentEnglish
A trained volunteer or staff guide who answers questions in the halls. A docent is your host; a curator is the scientist in charge of a collection.
Grade 7 Earth Science: Earth History and the Flood, Lesson 8.1 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 8.3 (grade 7)
A trained volunteer or staff guide who answers questions in the halls. A docent is your host; a curator is the scientist in charge of a collection.
Grade 7 Earth Science: Earth History and the Flood, Lesson 8.1 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 8.3 (grade 7)
doldrumsEnglish
A belt of light, shifting winds and calms near the equator, where sailing ships could sit still for days.
Grade 4 Earth Science: Weather and Water, Lesson 7.1 (grade 4)
A belt of light, shifting winds and calms near the equator, where sailing ships could sit still for days.
Grade 4 Earth Science: Weather and Water, Lesson 7.1 (grade 4)
domeEnglish
The round, turning roof of an observatory. A slit opens so the telescope can look out, and the dome turns to keep the slit in front of it.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.3 (grade 5) · Architecture & Civil Engineering, Lesson 1.3 (grade 9–12) · Grade 2 Engineering & Physics, Lesson 3.2 (grade 2) · +3 more
The round, turning roof of an observatory. A slit opens so the telescope can look out, and the dome turns to keep the slit in front of it.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.3 (grade 5) · Architecture & Civil Engineering, Lesson 1.3 (grade 9–12) · Grade 2 Engineering & Physics, Lesson 3.2 (grade 2) · +3 more
domestic animalEnglish
An animal people have raised and cared for over many generations, such as a cow, sheep, chicken, horse or dog.
Grade 3 Life Science: Plants and Animals Together, Lesson 9.3 (grade 3) · Grade 4 Life Science: Classification, Lesson 9.3 (grade 4) · Grade 6 Life Science: Animal Design and Behavior, Lesson 9.3 (grade 6) · +1 more
An animal people have raised and cared for over many generations, such as a cow, sheep, chicken, horse or dog.
Grade 3 Life Science: Plants and Animals Together, Lesson 9.3 (grade 3) · Grade 4 Life Science: Classification, Lesson 9.3 (grade 4) · Grade 6 Life Science: Animal Design and Behavior, Lesson 9.3 (grade 6) · +1 more
dominantEnglish
The side you prefer and use with more skill, such as your dominant hand, foot or eye.
Grade 5 Life Science: The Human Body, Lesson 6.2 (grade 5) · Grade 6 Life Science: Animal Design and Behavior, Lesson 4.2 (grade 6) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.2 (grade 8)
The side you prefer and use with more skill, such as your dominant hand, foot or eye.
Grade 5 Life Science: The Human Body, Lesson 6.2 (grade 5) · Grade 6 Life Science: Animal Design and Behavior, Lesson 4.2 (grade 6) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.2 (grade 8)
donorEnglish
A healthy person who gives blood so that someone else can receive it.
Grade 5 Life Science: The Human Body, Lesson 3.4 (grade 5)
A healthy person who gives blood so that someone else can receive it.
Grade 5 Life Science: The Human Body, Lesson 3.4 (grade 5)
Doppler radarEnglish
A radar that measures not only where rain and hail are but also how fast they move toward or away from the antenna, which reveals wind and rotation inside a storm.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.1 (grade 8) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 8.4 (grade 6)
A radar that measures not only where rain and hail are but also how fast they move toward or away from the antenna, which reveals wind and rotation inside a storm.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.1 (grade 8) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 8.4 (grade 6)
dormantEnglish
Resting and alive, but not growing yet. A dry seed is dormant until it gets water and warmth.
Grade 3 Life Science: Plants and Animals Together, Lesson 2.1 (grade 3)
Resting and alive, but not growing yet. A dry seed is dormant until it gets water and warmth.
Grade 3 Life Science: Plants and Animals Together, Lesson 2.1 (grade 3)
double helixEnglish
The shape of DNA: two strands wound around each other like a twisted ladder, about 2 nm wide, making one full turn every 3.4 nm (10 base pairs).
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.1 (grade 8)
The shape of DNA: two strands wound around each other like a twisted ladder, about 2 nm wide, making one full turn every 3.4 nm (10 base pairs).
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.1 (grade 8)
downhillEnglish
Toward the lower side. Water always runs downhill.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.2 (grade K)
Toward the lower side. Water always runs downhill.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.2 (grade K)
dragon bonesEnglish
The Chinese name (longgu) for fossil bones and teeth, mostly of mammals, dug up and sold by apothecaries for centuries.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.3 (grade 7)
The Chinese name (longgu) for fossil bones and teeth, mostly of mammals, dug up and sold by apothecaries for centuries.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.3 (grade 7)
drainEnglish
When water runs down through something and out the bottom.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 2.3 (grade 1) · Grade 2 Engineering & Physics, Lesson 5.4 (grade 2) · Kindergarten Engineering & Physics, Lesson 5.2 (grade K)
When water runs down through something and out the bottom.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 2.3 (grade 1) · Grade 2 Engineering & Physics, Lesson 5.4 (grade 2) · Kindergarten Engineering & Physics, Lesson 5.2 (grade K)
drawdownEnglish
The distance the water level in a well drops below its resting (static) level while the well is being pumped.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.3 (grade 8)
The distance the water level in a well drops below its resting (static) level while the well is being pumped.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.3 (grade 8)
dress and keepEnglish
Adam’s job in the garden. To dress is to work it: dig, plant and water. To keep is to guard it and care for it.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 8.1 (grade K)
Adam’s job in the garden. To dress is to work it: dig, plant and water. To keep is to guard it and care for it.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 8.1 (grade K)
driller’s logEnglish
The written record a driller keeps of every layer passed through, with its depth, color and material, and where water was found.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.3 (grade 8)
The written record a driller keeps of every layer passed through, with its depth, color and material, and where water was found.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.3 (grade 8)
drilling mudEnglish
A heavy mixture of water, clay and minerals pumped down a well. It cools the bit, carries chips up, plasters the hole’s walls, and its weight holds back oil and gas.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.2 (grade 8)
A heavy mixture of water, clay and minerals pumped down a well. It cools the bit, carries chips up, plasters the hole’s walls, and its weight holds back oil and gas.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.2 (grade 8)
dripEnglish
One little drop of water falling, again and again, from a faucet that is not shut tight.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 8.3 (grade K)
One little drop of water falling, again and again, from a faucet that is not shut tight.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 8.3 (grade K)
drip tipEnglish
A long, pointed tip on a leaf that lets rainwater run off quickly.
Grade 3 Life Science: Plants and Animals Together, Lesson 5.2 (grade 3)
A long, pointed tip on a leaf that lets rainwater run off quickly.
Grade 3 Life Science: Plants and Animals Together, Lesson 5.2 (grade 3)
drive pipe (casing)English
An iron pipe driven down through loose soil and gravel to bedrock so the hole will not cave in. Every modern well is still lined with steel casing.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.1 (grade 8)
An iron pipe driven down through loose soil and gravel to bedrock so the hole will not cave in. Every modern well is still lined with steel casing.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.1 (grade 8)
dromedaryEnglish
A camel with one hump. Dromedaries live in the hot deserts of Arabia and North Africa.
Grade 1 Life Science: Animal Homes and Habits, Lesson 4.1 (grade 1)
A camel with one hump. Dromedaries live in the hot deserts of Arabia and North Africa.
Grade 1 Life Science: Animal Homes and Habits, Lesson 4.1 (grade 1)
Drop, Cover and Hold OnEnglish
The earthquake action: drop to hands and knees, cover your head and neck under a sturdy table or beside an inside wall, and hold on until the shaking stops.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.4 (grade 6)
The earthquake action: drop to hands and knees, cover your head and neck under a sturdy table or beside an inside wall, and hold on until the shaking stops.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.4 (grade 6)
droughtEnglish
A long time with little or no rain, when the ground gets dry and plants cannot grow.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 4.4 (grade 1) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.1 (grade 8) · Grade 1 Life Science: Animal Homes and Habits, Lesson 4.4 (grade 1)
A long time with little or no rain, when the ground gets dry and plants cannot grow.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 4.4 (grade 1) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.1 (grade 8) · Grade 1 Life Science: Animal Homes and Habits, Lesson 4.4 (grade 1)
dry dayEnglish
A day when no rain falls, so the gauge reads zero.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.2 (grade 1)
A day when no rain falls, so the gauge reads zero.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.2 (grade 1)
dry massEnglish
The mass of a plant or soil sample after all its water has been dried out. Scientists use dry mass to see how much real building material a plant has made.
Grade 7 Life Science: Cells and Microbes, Lesson 5.1 (grade 7)
The mass of a plant or soil sample after all its water has been dried out. Scientists use dry mass to see how much real building material a plant has made.
Grade 7 Life Science: Cells and Microbes, Lesson 5.1 (grade 7)
dry mountEnglish
A slide on which a dry specimen, such as a hair, a feather barb or salt grains, is placed under a coverslip without water.
Grade 7 Life Science: Cells and Microbes, Lesson 1.3 (grade 7)
A slide on which a dry specimen, such as a hair, a feather barb or salt grains, is placed under a coverslip without water.
Grade 7 Life Science: Cells and Microbes, Lesson 1.3 (grade 7)
duck-billed dinosaurEnglish
A plant-eating dinosaur with a wide, flat beak, a little like a duck’s bill. Scientists also call it a hadrosaur.
Grade 1 Life Science: Animal Homes and Habits, Lesson 7.3 (grade 1)
A plant-eating dinosaur with a wide, flat beak, a little like a duck’s bill. Scientists also call it a hadrosaur.
Grade 1 Life Science: Animal Homes and Habits, Lesson 7.3 (grade 1)
ducklingEnglish
A baby duck. It is covered in soft fluffy feathers and follows its mother everywhere.
Grade 1 Life Science: Animal Homes and Habits, Lesson 2.2 (grade 1)
A baby duck. It is covered in soft fluffy feathers and follows its mother everywhere.
Grade 1 Life Science: Animal Homes and Habits, Lesson 2.2 (grade 1)
ductileEnglish
Bending or flowing without breaking when stressed, like warm wax or wet clay. Ductile rock makes folds.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.2 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 8.1 (grade 6)
Bending or flowing without breaking when stressed, like warm wax or wet clay. Ductile rock makes folds.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.2 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 8.1 (grade 6)
dug wellEnglish
A hole dug by hand down past the water table, usually lined with stone, so groundwater seeps in and can be lifted out with a bucket.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.1 (grade 8)
A hole dug by hand down past the water table, usually lined with stone, so groundwater seeps in and can be lifted out with a bucket.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.1 (grade 8)
duneEnglish
A mound or ridge of wind-blown sand with a gentle windward slope and a steep downwind slip face. Barchan dunes are crescents with horns pointing downwind.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.3 (grade 6)
A mound or ridge of wind-blown sand with a gentle windward slope and a steep downwind slip face. Barchan dunes are crescents with horns pointing downwind.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.3 (grade 6)
E
earEnglish
The part of your body God made for hearing. The outside part catches sound and the inside part feels it.
Grade 1 Life Science: Animal Homes and Habits, Lesson 8.2 (grade 1)
The part of your body God made for hearing. The outside part catches sound and the inside part feels it.
Grade 1 Life Science: Animal Homes and Habits, Lesson 8.2 (grade 1)
eardrumEnglish
A thin, tight skin deep inside your ear. It shakes when sound reaches it, like the top of a little drum.
Grade 1 Life Science: Animal Homes and Habits, Lesson 8.2 (grade 1) · Grade 5 Life Science: The Human Body, Lesson 7.2 (grade 5)
A thin, tight skin deep inside your ear. It shakes when sound reaches it, like the top of a little drum.
Grade 1 Life Science: Animal Homes and Habits, Lesson 8.2 (grade 1) · Grade 5 Life Science: The Human Body, Lesson 7.2 (grade 5)
early warningEnglish
An alert sent seconds to hours before danger arrives, such as the USGS ShakeAlert system for earthquakes or a tsunami warning from NOAA.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.4 (grade 6)
An alert sent seconds to hours before danger arrives, such as the USGS ShakeAlert system for earthquakes or a tsunami warning from NOAA.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.4 (grade 6)
earsEnglish
The parts on the sides of your head that catch sounds.
Kindergarten Life Science: God Made the Animals, Lesson 6.3 (grade K)
The parts on the sides of your head that catch sounds.
Kindergarten Life Science: God Made the Animals, Lesson 6.3 (grade K)
earthquakeEnglish
A sudden shaking of the ground.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.1 (grade 2) · Grade 2 Earth Science: The Earth's Surface, Lesson 9.3 (grade 2) · Grade 4 Engineering & Physics, Lesson 3.4 (grade 4) · +1 more
A sudden shaking of the ground.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.1 (grade 2) · Grade 2 Earth Science: The Earth's Surface, Lesson 9.3 (grade 2) · Grade 4 Engineering & Physics, Lesson 3.4 (grade 4) · +1 more
earthquake swarmEnglish
Many small earthquakes close together in time and place, often caused by magma forcing its way through rock.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.2 (grade 6)
Many small earthquakes close together in time and place, often caused by magma forcing its way through rock.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.2 (grade 6)
earthshineEnglish
A faint glow on the dark part of a crescent Moon, made by sunlight bouncing off Earth onto the Moon.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.3 (grade 5)
A faint glow on the dark part of a crescent Moon, made by sunlight bouncing off Earth onto the Moon.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.3 (grade 5)
earthwormEnglish
A long, soft animal with no legs and no bones that lives in the soil.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.2 (grade K) · Grade 1 Gardening & Animals, Lesson 3.2 (grade 1) · Grade 2 Gardening & Animals, Lesson 3.4 (grade 2) · +1 more
A long, soft animal with no legs and no bones that lives in the soil.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.2 (grade K) · Grade 1 Gardening & Animals, Lesson 3.2 (grade 1) · Grade 2 Gardening & Animals, Lesson 3.4 (grade 2) · +1 more
eastEnglish
The side of the sky where the sun comes up every morning.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 5.1 (grade K)
The side of the sky where the sun comes up every morning.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 5.1 (grade K)
eccentricityEnglish
A number that tells how stretched an ellipse is: the distance between the foci divided by the length of the major axis. A circle has eccentricity 0.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.2 (grade 5) · Architecture & Civil Engineering, Lesson 8.3 (grade 9–12) · Physics, Lesson 4.3 (grade 11–12)
A number that tells how stretched an ellipse is: the distance between the foci divided by the length of the major axis. A circle has eccentricity 0.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.2 (grade 5) · Architecture & Civil Engineering, Lesson 8.3 (grade 9–12) · Physics, Lesson 4.3 (grade 11–12)
echinodermEnglish
A sea animal with spiny or bumpy skin, tube feet and body parts arranged around a center, such as a sea star, sea urchin, sand dollar or sea cucumber. The name means “spiny skin.”
Grade 4 Life Science: Classification, Lesson 3.4 (grade 4)
A sea animal with spiny or bumpy skin, tube feet and body parts arranged around a center, such as a sea star, sea urchin, sand dollar or sea cucumber. The name means “spiny skin.”
Grade 4 Life Science: Classification, Lesson 3.4 (grade 4)
echoEnglish
A sound that bounces off something and comes back to you.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.3 (grade 2) · Grade 6 Engineering & Physics, Lesson 8.3 (grade 6) · Explore Animals · Ranger, Stop 6.1 (Ages 10–13) · +3 more
A sound that bounces off something and comes back to you.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.3 (grade 2) · Grade 6 Engineering & Physics, Lesson 8.3 (grade 6) · Explore Animals · Ranger, Stop 6.1 (Ages 10–13) · +3 more
echo sounderEnglish
A sonar pointed straight down from a ship to measure the depth of the water from the echo time.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.3 (grade 6)
A sonar pointed straight down from a ship to measure the depth of the water from the echo time.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.3 (grade 6)
echolocationEnglish
Finding things by making sounds and listening for the echoes. Bats do it to find bugs in the dark.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.3 (grade 2) · Explore Animals · Expert, Stop 1.4 (Ages 14+) · Explore Animals · Expert, Stop 4.5 (Ages 14+) · +3 more
Finding things by making sounds and listening for the echoes. Bats do it to find bugs in the dark.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.3 (grade 2) · Explore Animals · Expert, Stop 1.4 (Ages 14+) · Explore Animals · Expert, Stop 4.5 (Ages 14+) · +3 more
eclipticEnglish
The narrow path across the sky that the Sun seems to follow through the year. The Moon and planets always stay close to it.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.1 (grade 5)
The narrow path across the sky that the Sun seems to follow through the year. The Moon and planets always stay close to it.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.1 (grade 5)
ecological zonationEnglish
The creation reading of fossil order: creatures were buried roughly in the order of where they lived, from the sea floor upward, as the Flood waters rose.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.2 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.4 (grade 8)
The creation reading of fossil order: creatures were buried roughly in the order of where they lived, from the sea floor upward, as the Flood waters rose.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.2 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.4 (grade 8)
ecosystemEnglish
All the living things in an area together with the nonliving things around them, such as sunlight, water, soil and air, working as one system.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 7.1 (grade 8)
All the living things in an area together with the nonliving things around them, such as sunlight, water, soil and air, working as one system.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 7.1 (grade 8)
ecosystem engineerEnglish
An animal that changes its surroundings so much that it creates new homes for many other living things.
Grade 6 Life Science: Animal Design and Behavior, Lesson 5.3 (grade 6)
An animal that changes its surroundings so much that it creates new homes for many other living things.
Grade 6 Life Science: Animal Design and Behavior, Lesson 5.3 (grade 6)
edemaEnglish
Swelling caused when fluid is pushed out of the blood vessels into the surrounding tissues, often in the lower legs.
Grade 7 Life Science: Cells and Microbes, Lesson 7.4 (grade 7)
Swelling caused when fluid is pushed out of the blood vessels into the surrounding tissues, often in the lower legs.
Grade 7 Life Science: Cells and Microbes, Lesson 7.4 (grade 7)
EEGEnglish
Electroencephalogram: a machine that records the brain’s tiny electrical waves through small sensors placed on the scalp.
Grade 5 Life Science: The Human Body, Lesson 6.4 (grade 5)
Electroencephalogram: a machine that records the brain’s tiny electrical waves through small sensors placed on the scalp.
Grade 5 Life Science: The Human Body, Lesson 6.4 (grade 5)
eftEnglish
A young newt that lives on land for a while before it goes back to the water. The red eft is bright orange-red.
Grade 2 Life Science: Animal Families, Lesson 4.3 (grade 2)
A young newt that lives on land for a while before it goes back to the water. The red eft is bright orange-red.
Grade 2 Life Science: Animal Families, Lesson 4.3 (grade 2)
eggEnglish
A shell with a baby animal growing inside. Birds, turtles and dinosaurs lay eggs.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.4 (grade 1) · Kindergarten Life Science: God Made the Animals, Lesson 3.2 (grade K) · Kindergarten Life Science: God Made the Animals, Lesson 7.4 (grade K)
A shell with a baby animal growing inside. Birds, turtles and dinosaurs lay eggs.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.4 (grade 1) · Kindergarten Life Science: God Made the Animals, Lesson 3.2 (grade K) · Kindergarten Life Science: God Made the Animals, Lesson 7.4 (grade K)
egg massEnglish
A clump of many frog eggs held together in clear jelly. It is also called frog spawn.
Grade 2 Life Science: Animal Families, Lesson 4.2 (grade 2)
A clump of many frog eggs held together in clear jelly. It is also called frog spawn.
Grade 2 Life Science: Animal Families, Lesson 4.2 (grade 2)
egg-laying mammalEnglish
A mammal whose babies hatch from eggs. Only the platypus and the spiny echidnas are mammals like this.
Grade 2 Life Science: Animal Families, Lesson 1.4 (grade 2)
A mammal whose babies hatch from eggs. Only the platypus and the spiny echidnas are mammals like this.
Grade 2 Life Science: Animal Families, Lesson 1.4 (grade 2)
eggshell poresEnglish
Tiny channels through an eggshell that let oxygen in and carbon dioxide and water vapor out. Their number and size hint at whether an egg was buried or sat in open air.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.2 (grade 7)
Tiny channels through an eggshell that let oxygen in and carbon dioxide and water vapor out. Their number and size hint at whether an egg was buried or sat in open air.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.2 (grade 7)
elastic reboundEnglish
Rock on both sides of a fault bends slowly and stores energy, then snaps back when friction gives way, sending out seismic waves.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.1 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 3.3 (grade 6)
Rock on both sides of a fault bends slowly and stores energy, then snaps back when friction gives way, sending out seismic waves.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.1 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 3.3 (grade 6)
electric currentEnglish
A flow of electric charge. Every electric current makes a magnetic field around it.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.4 (grade 6) · Electronics & Microcontrollers, Lesson 1.1 (grade 9–12) · Grade 4 Engineering & Physics, Lesson 4.1 (grade 4)
A flow of electric charge. Every electric current makes a magnetic field around it.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.4 (grade 6) · Electronics & Microcontrollers, Lesson 1.1 (grade 9–12) · Grade 4 Engineering & Physics, Lesson 4.1 (grade 4)
embryoEnglish
A young animal developing inside its egg. Fossil embryos inside dinosaur eggs are rare and prove which animal laid the egg.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.2 (grade 7) · Explore Dinosaurs · Expert, Stop 2.8 (Ages 14+) · Explore Dinosaurs · Expert, Stop 3.2 (Ages 14+) · +3 more
A young animal developing inside its egg. Fossil embryos inside dinosaur eggs are rare and prove which animal laid the egg.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.2 (grade 7) · Explore Dinosaurs · Expert, Stop 2.8 (Ages 14+) · Explore Dinosaurs · Expert, Stop 3.2 (Ages 14+) · +3 more
emergency kitEnglish
A box or bag of supplies, such as water, food, a flashlight, a radio and first-aid items, ready to use when a storm cuts off power or travel.
Grade 4 Earth Science: Weather and Water, Lesson 4.4 (grade 4) · Grade 6 Earth Science: The Dynamic Earth, Lesson 8.4 (grade 6)
A box or bag of supplies, such as water, food, a flashlight, a radio and first-aid items, ready to use when a storm cuts off power or travel.
Grade 4 Earth Science: Weather and Water, Lesson 4.4 (grade 4) · Grade 6 Earth Science: The Dynamic Earth, Lesson 8.4 (grade 6)
emphysemaEnglish
A lung disease, often caused by smoking, in which the walls of the alveoli break down, leaving fewer, larger air sacs and making it hard to breathe.
Grade 5 Life Science: The Human Body, Lesson 4.4 (grade 5)
A lung disease, often caused by smoking, in which the walls of the alveoli break down, leaving fewer, larger air sacs and making it hard to breathe.
Grade 5 Life Science: The Human Body, Lesson 4.4 (grade 5)
enamelEnglish
The hard, shiny outer layer of the crown of a tooth; the hardest material in the human body.
Grade 5 Life Science: The Human Body, Lesson 5.2 (grade 5)
The hard, shiny outer layer of the crown of a tooth; the hardest material in the human body.
Grade 5 Life Science: The Human Body, Lesson 5.2 (grade 5)
endangeredEnglish
So few left that a kind of animal might disappear from the wild unless people help.
Grade 2 Life Science: Animal Families, Lesson 2.4 (grade 2)
So few left that a kind of animal might disappear from the wild unless people help.
Grade 2 Life Science: Animal Families, Lesson 2.4 (grade 2)
endosporeEnglish
A tough, resting form that some bacteria make when conditions turn harsh. It can survive boiling, drying and years of waiting, then grow again.
Grade 7 Life Science: Cells and Microbes, Lesson 3.1 (grade 7)
A tough, resting form that some bacteria make when conditions turn harsh. It can survive boiling, drying and years of waiting, then grow again.
Grade 7 Life Science: Cells and Microbes, Lesson 3.1 (grade 7)
Enhanced Fujita (EF) scaleEnglish
A scale from EF0 to EF5 that rates a tornado by estimating its winds from the damage it leaves.
Grade 4 Earth Science: Weather and Water, Lesson 4.2 (grade 4) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.2 (grade 8) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 8.4 (grade 6)
A scale from EF0 to EF5 that rates a tornado by estimating its winds from the damage it leaves.
Grade 4 Earth Science: Weather and Water, Lesson 4.2 (grade 4) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.2 (grade 8) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 8.4 (grade 6)
epicEnglish
A long poem telling the deeds of a hero. The Epic of Gilgamesh includes a flood story on its eleventh tablet.
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.3 (grade 7) · Grade 7 Greek, Lesson 1.1 (grade 7) · Grade 8 Greek, Lesson 3.1 (grade 8) · +1 more
A long poem telling the deeds of a hero. The Epic of Gilgamesh includes a flood story on its eleventh tablet.
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.3 (grade 7) · Grade 7 Greek, Lesson 1.1 (grade 7) · Grade 8 Greek, Lesson 3.1 (grade 8) · +1 more
epicenterEnglish
The point on the earth’s surface directly above the focus.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.1 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 3.3 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 9.2 (grade 6) · +1 more
The point on the earth’s surface directly above the focus.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.1 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 3.3 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 9.2 (grade 6) · +1 more
equatorial sundialEnglish
A sundial whose face is tilted to lie parallel to Earth’s equator, with its gnomon pointing along Earth’s axis toward Polaris. Its hour lines are evenly spaced, 15° apart.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.1 (grade 5)
A sundial whose face is tilted to lie parallel to Earth’s equator, with its gnomon pointing along Earth’s axis toward Polaris. Its hour lines are evenly spaced, 15° apart.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.1 (grade 5)
equinoxEnglish
One of the two days each year, about March 20 and September 22, when day and night are nearly equal everywhere on Earth. From Latin words meaning “equal night.”
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.2 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.2 (grade 5) · Grade 3 Gardening & Animals, Lesson 1.2 (grade 3) · +3 more
One of the two days each year, about March 20 and September 22, when day and night are nearly equal everywhere on Earth. From Latin words meaning “equal night.”
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.2 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.2 (grade 5) · Grade 3 Gardening & Animals, Lesson 1.2 (grade 3) · +3 more
erosion pinEnglish
A nail or stake driven into the ground with its top at a known height, so that later measurements show whether soil was lost or gained.
Grade 6 Earth Science: The Dynamic Earth, Lesson 9.1 (grade 6)
A nail or stake driven into the ground with its top at a known height, so that later measurements show whether soil was lost or gained.
Grade 6 Earth Science: The Dynamic Earth, Lesson 9.1 (grade 6)
erraticEnglish
A boulder of rock that does not match the bedrock where it sits, carried there by ice or by floodwater rafting icebergs.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.1 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 4.4 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 5.1 (grade 7) · +2 more
A boulder of rock that does not match the bedrock where it sits, carried there by ice or by floodwater rafting icebergs.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.1 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 4.4 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 5.1 (grade 7) · +2 more
errorEnglish
How far a forecast missed. For temperature, it is the difference between the forecast and the measured temperature.
Grade 4 Earth Science: Weather and Water, Lesson 5.4 (grade 4) · Engineering Design, Robotics & Drones, Lesson 7.3 (grade 9–12) · Grade 7 Engineering & Physics, Lesson 8.2 (grade 7)
How far a forecast missed. For temperature, it is the difference between the forecast and the measured temperature.
Grade 4 Earth Science: Weather and Water, Lesson 5.4 (grade 4) · Engineering Design, Robotics & Drones, Lesson 7.3 (grade 9–12) · Grade 7 Engineering & Physics, Lesson 8.2 (grade 7)
error rangeEnglish
The plus-or-minus figure printed with a date, showing how far the measurement could be off; two dates agree if their ranges overlap.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.4 (grade 7)
The plus-or-minus figure printed with a date, showing how far the measurement could be off; two dates agree if their ranges overlap.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.4 (grade 7)
eruptionEnglish
When a volcano pushes out ash, gas or lava.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.1 (grade 2)
When a volcano pushes out ash, gas or lava.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.1 (grade 2)
eruption columnEnglish
The tall, rising cloud of hot gas, ash and pumice that a powerful volcano pushes into the sky, sometimes more than 30 km high.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.1 (grade 6)
The tall, rising cloud of hot gas, ash and pumice that a powerful volcano pushes into the sky, sometimes more than 30 km high.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.1 (grade 6)
esophagusEnglish
The muscular tube, about 25 cm (10 inches) long, that carries swallowed food from the throat to the stomach.
Grade 5 Life Science: The Human Body, Lesson 5.3 (grade 5)
The muscular tube, about 25 cm (10 inches) long, that carries swallowed food from the throat to the stomach.
Grade 5 Life Science: The Human Body, Lesson 5.3 (grade 5)
estimateEnglish
A careful, reasoned guess at a number that is too large or too hard to count one by one.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.1 (grade 5) · Explore Dinosaurs · Ranger, Stop 1.1 (Ages 10–13) · Explore Dinosaurs · Ranger, Stop 3.5 (Ages 10–13) · +3 more
A careful, reasoned guess at a number that is too large or too hard to count one by one.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.1 (grade 5) · Explore Dinosaurs · Ranger, Stop 1.1 (Ages 10–13) · Explore Dinosaurs · Ranger, Stop 3.5 (Ages 10–13) · +3 more
estivationEnglish
A deep rest some animals take during hot, dry weather, like hibernation in summer.
Grade 4 Life Science: Classification, Lesson 3.3 (grade 4)
A deep rest some animals take during hot, dry weather, like hibernation in summer.
Grade 4 Life Science: Classification, Lesson 3.3 (grade 4)
ethogramEnglish
A list of an animal’s behaviors, each with a short definition, used to record what the animal does during a watch.
Grade 6 Life Science: Animal Design and Behavior, Lesson 9.3 (grade 6) · Grade 7 Life Science: Cells and Microbes, Lesson 9.3 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 9.3 (grade 8)
A list of an animal’s behaviors, each with a short definition, used to record what the animal does during a watch.
Grade 6 Life Science: Animal Design and Behavior, Lesson 9.3 (grade 6) · Grade 7 Life Science: Cells and Microbes, Lesson 9.3 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 9.3 (grade 8)
evacuateEnglish
To leave an area that is in danger, such as a low coast before a hurricane, and go to a safer place.
Grade 4 Earth Science: Weather and Water, Lesson 4.4 (grade 4)
To leave an area that is in danger, such as a low coast before a hurricane, and go to a safer place.
Grade 4 Earth Science: Weather and Water, Lesson 4.4 (grade 4)
evergreenEnglish
A tree, like a pine or a spruce, that keeps its green needles or leaves all winter long.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.4 (grade K) · Grade 2 Geography: Our Country, Coast to Coast, Lesson 5.2 (grade 2) · Grade 1 Life Science: Animal Homes and Habits, Lesson 6.1 (grade 1) · +1 more
A tree, like a pine or a spruce, that keeps its green needles or leaves all winter long.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.4 (grade K) · Grade 2 Geography: Our Country, Coast to Coast, Lesson 5.2 (grade 2) · Grade 1 Life Science: Animal Homes and Habits, Lesson 6.1 (grade 1) · +1 more
excavateEnglish
To dig something out of the ground slowly and carefully so it is not broken.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.1 (grade 3) · Explore Dinosaurs, Stop 2.7 (Ages 7–9) · Explore Dinosaurs, Stop 5.9 (Ages 7–9)
To dig something out of the ground slowly and carefully so it is not broken.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.1 (grade 3) · Explore Dinosaurs, Stop 2.7 (Ages 7–9) · Explore Dinosaurs, Stop 5.9 (Ages 7–9)
exceptional preservationEnglish
Fossils that keep soft parts such as guts, gills, muscles or eyes, not only shells and bones. It usually requires very rapid burial in fine sediment with little oxygen.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.1 (grade 8)
Fossils that keep soft parts such as guts, gills, muscles or eyes, not only shells and bones. It usually requires very rapid burial in fine sediment with little oxygen.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.1 (grade 8)
excess argonEnglish
Argon-40 in a rock that did not come from potassium decay after the rock hardened, but was trapped from the magma or inherited in older crystals. It makes a rock read older than it is.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.4 (grade 7)
Argon-40 in a rock that did not come from potassium decay after the rock hardened, but was trapped from the magma or inherited in older crystals. It makes a rock read older than it is.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.4 (grade 7)
exoskeletonEnglish
A hard skeleton on the outside of the body, like a suit of armor.
Grade 4 Life Science: Classification, Lesson 3.1 (grade 4) · Grade 6 Life Science: Animal Design and Behavior, Lesson 1.3 (grade 6) · Grade 7 Life Science: Cells and Microbes, Lesson 7.3 (grade 7)
A hard skeleton on the outside of the body, like a suit of armor.
Grade 4 Life Science: Classification, Lesson 3.1 (grade 4) · Grade 6 Life Science: Animal Design and Behavior, Lesson 1.3 (grade 6) · Grade 7 Life Science: Cells and Microbes, Lesson 7.3 (grade 7)
expected ratioEnglish
The ratio of offspring types a Punnett square predicts on average, such as 3 : 1 or 9 : 3 : 3 : 1.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.3 (grade 8)
The ratio of offspring types a Punnett square predicts on average, such as 3 : 1 or 9 : 3 : 3 : 1.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.3 (grade 8)
expeditionEnglish
A long trip made by a team to explore and find out new things.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.4 (grade 1) · Explore Dinosaurs · Ranger, Stop 2.8 (Ages 10–13) · Explore Dinosaurs, Stop 2.6 (Ages 7–9) · +3 more
A long trip made by a team to explore and find out new things.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.4 (grade 1) · Explore Dinosaurs · Ranger, Stop 2.8 (Ages 10–13) · Explore Dinosaurs, Stop 2.6 (Ages 7–9) · +3 more
explorerEnglish
A person who travels to new places to find out what is there.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.1 (grade 2) · Grade 2 Earth Science: The Earth's Surface, Lesson 8.1 (grade 2) · Grade 1 Geography: Maps and Journeys, Lesson 8.1 (grade 1) · +1 more
A person who travels to new places to find out what is there.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.1 (grade 2) · Grade 2 Earth Science: The Earth's Surface, Lesson 8.1 (grade 2) · Grade 1 Geography: Maps and Journeys, Lesson 8.1 (grade 1) · +1 more
extent of the FloodEnglish
Whether the Flood of Genesis 6 to 9 covered the whole earth (global) or a large region (local); young-earth Christians hold it was global, and old-earth Christians are divided.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.2 (grade 8)
Whether the Flood of Genesis 6 to 9 covered the whole earth (global) or a large region (local); young-earth Christians hold it was global, and old-earth Christians are divided.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.2 (grade 8)
extractionEnglish
Separating one substance, such as DNA, from everything else in a mixture.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.2 (grade 8)
Separating one substance, such as DNA, from everything else in a mixture.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.2 (grade 8)
eyeEnglish
The calm, often clear center of a hurricane, where air sinks slowly.
Grade 4 Earth Science: Weather and Water, Lesson 4.1 (grade 4) · Explore Crafts and Making · Expert, Stop 1.1 (Ages 14+) · Explore Crafts and Making · Ranger, Stop 1.2 (Ages 10–13) · +3 more
The calm, often clear center of a hurricane, where air sinks slowly.
Grade 4 Earth Science: Weather and Water, Lesson 4.1 (grade 4) · Explore Crafts and Making · Expert, Stop 1.1 (Ages 14+) · Explore Crafts and Making · Ranger, Stop 1.2 (Ages 10–13) · +3 more
eye ringEnglish
A thin circle of pale or colored feathers around a bird’s eye.
Grade 4 Life Science: Classification, Lesson 4.4 (grade 4)
A thin circle of pale or colored feathers around a bird’s eye.
Grade 4 Life Science: Classification, Lesson 4.4 (grade 4)
eyelidEnglish
The flap of skin that closes over your eye to keep it safe and wet.
Grade 1 Life Science: Animal Homes and Habits, Lesson 8.1 (grade 1)
The flap of skin that closes over your eye to keep it safe and wet.
Grade 1 Life Science: Animal Homes and Habits, Lesson 8.1 (grade 1)
eyepieceEnglish
The small lens you put your eye to. It works like a magnifying glass to enlarge the image made by the objective.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.1 (grade 5)
The small lens you put your eye to. It works like a magnifying glass to enlarge the image made by the objective.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.1 (grade 5)
eyepiece (ocular)English
The lens you look into at the top of the microscope, usually 10×.
Grade 7 Life Science: Cells and Microbes, Lesson 1.2 (grade 7)
The lens you look into at the top of the microscope, usually 10×.
Grade 7 Life Science: Cells and Microbes, Lesson 1.2 (grade 7)
eyesEnglish
The two round parts in your face that see light, colors and shapes.
Kindergarten Life Science: God Made the Animals, Lesson 6.3 (grade K)
The two round parts in your face that see light, colors and shapes.
Kindergarten Life Science: God Made the Animals, Lesson 6.3 (grade K)
eyespotEnglish
A simple eye at the tip of each sea star arm that can tell light from dark and see large shapes.
Grade 4 Life Science: Classification, Lesson 3.4 (grade 4)
A simple eye at the tip of each sea star arm that can tell light from dark and see large shapes.
Grade 4 Life Science: Classification, Lesson 3.4 (grade 4)
eyewallEnglish
The ring of tall thunderstorm clouds around the eye, where the strongest winds and heaviest rain are.
Grade 4 Earth Science: Weather and Water, Lesson 4.1 (grade 4)
The ring of tall thunderstorm clouds around the eye, where the strongest winds and heaviest rain are.
Grade 4 Earth Science: Weather and Water, Lesson 4.1 (grade 4)
F
fair summaryEnglish
A restatement of someone else’s view, in its own terms and with its best evidence, that the holder of the view would accept as accurate; sometimes called a steel-man.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.4 (grade 8)
A restatement of someone else’s view, in its own terms and with its best evidence, that the holder of the view would accept as accurate; sometimes called a steel-man.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.4 (grade 8)
fair-weather cumulusEnglish
Small, flat-bottomed, puffy clouds spread far apart that do not grow tall. They usually mean dry weather.
Grade 4 Earth Science: Weather and Water, Lesson 3.2 (grade 4)
Small, flat-bottomed, puffy clouds spread far apart that do not grow tall. They usually mean dry weather.
Grade 4 Earth Science: Weather and Water, Lesson 3.2 (grade 4)
fallEnglish
The season after summer, when the days grow shorter and cooler and many trees drop their leaves. Fall is also called autumn.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.3 (grade K) · Explore Dinosaurs · Expert, Stop 4.1 (Ages 14+) · Kindergarten Gardening & Animals, Lesson 1.1 (grade K)
The season after summer, when the days grow shorter and cooler and many trees drop their leaves. Fall is also called autumn.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.3 (grade K) · Explore Dinosaurs · Expert, Stop 4.1 (Ages 14+) · Kindergarten Gardening & Animals, Lesson 1.1 (grade K)
fallenEnglish
Dropped to the ground on its own, like a dry leaf, an acorn or a pinecone.
Grade 1 Life Science: Animal Homes and Habits, Lesson 9.4 (grade 1)
Dropped to the ground on its own, like a dry leaf, an acorn or a pinecone.
Grade 1 Life Science: Animal Homes and Habits, Lesson 9.4 (grade 1)
falling pressureEnglish
Air pressure going down over hours or days. It often means clouds, rain or a storm are coming.
Grade 4 Earth Science: Weather and Water, Lesson 2.2 (grade 4)
Air pressure going down over hours or days. It often means clouds, rain or a storm are coming.
Grade 4 Earth Science: Weather and Water, Lesson 2.2 (grade 4)
False CrossEnglish
A larger, dimmer cross-shaped group of stars near the Southern Cross that can fool beginners. It has no Pointers beside it.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.3 (grade 5)
A larger, dimmer cross-shaped group of stars near the Southern Cross that can fool beginners. It has no Pointers beside it.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.3 (grade 5)
family planEnglish
Written agreements about where to meet, whom to call and what each person does when a hazard strikes, practiced ahead of time.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.4 (grade 6)
Written agreements about where to meet, whom to call and what each person does when a hazard strikes, practiced ahead of time.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.4 (grade 6)
family (rank)English
The Linnaean rank above genus and below order, such as the cat family (Felidae) or the dog family (Canidae).
Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.4 (grade 8)
The Linnaean rank above genus and below order, such as the cat family (Felidae) or the dog family (Canidae).
Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.4 (grade 8)
family unitEnglish
A close group of related female elephants (mothers, daughters, sisters and aunts) and their young, who live and travel together.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.3 (grade 6)
A close group of related female elephants (mothers, daughters, sisters and aunts) and their young, who live and travel together.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.3 (grade 6)
farm animalEnglish
An animal people raise for food, wool, eggs or work, such as a cow, a sheep, a hen or a horse.
Grade 1 Life Science: Animal Homes and Habits, Lesson 9.3 (grade 1)
An animal people raise for food, wool, eggs or work, such as a cow, a sheep, a hen or a horse.
Grade 1 Life Science: Animal Homes and Habits, Lesson 9.3 (grade 1)
faucetEnglish
The handle and spout at a sink or tub that lets water out of the pipes. You can turn it on and turn it off.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 8.3 (grade K)
The handle and spout at a sink or tub that lets water out of the pipes. You can turn it on and turn it off.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 8.3 (grade K)
faultEnglish
A long crack in the earth’s rock where two big pieces of rock can slip past each other.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.1 (grade 2) · Grade 6 Earth Science: The Dynamic Earth, Lesson 4.1 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 5.1 (grade 6) · +3 more
A long crack in the earth’s rock where two big pieces of rock can slip past each other.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.1 (grade 2) · Grade 6 Earth Science: The Dynamic Earth, Lesson 4.1 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 5.1 (grade 6) · +3 more
fault scarpEnglish
A small cliff at the surface made where one side of a fault has moved up or down.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.1 (grade 6)
A small cliff at the surface made where one side of a fault has moved up or down.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.1 (grade 6)
faunal successionEnglish
William Smith’s rule: fossils occur in a definite order through the layers, so a layer can be recognized by the fossils it holds.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.2 (grade 7) · High School Geology, Lesson 5.3 (grade 9–12)
William Smith’s rule: fossils occur in a definite order through the layers, so a layer can be recognized by the fossils it holds.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.2 (grade 7) · High School Geology, Lesson 5.3 (grade 9–12)
felsicEnglish
Igneous rock rich in feldspar and silica, light in color and low in iron and magnesium; the opposite is mafic.
High School Geology, Lesson 1.2 (grade 9–12)
Igneous rock rich in feldspar and silica, light in color and low in iron and magnesium; the opposite is mafic.
High School Geology, Lesson 1.2 (grade 9–12)
fertilizer gradeEnglish
The three numbers on a fertilizer bag, such as 10-10-10, giving the percent by mass of nitrogen, phosphate (P₂O₅) and potash (K₂O).
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.4 (grade 8)
The three numbers on a fertilizer bag, such as 10-10-10, giving the percent by mass of nitrogen, phosphate (P₂O₅) and potash (K₂O).
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.4 (grade 8)
field guideEnglish
A book or chart that helps people identify plants, animals or rocks outdoors, often with pictures and keys.
Grade 4 Life Science: Classification, Lesson 1.4 (grade 4) · Grade 4 Life Science: Classification, Lesson 4.4 (grade 4) · Grade 4 Life Science: Classification, Lesson 8.1 (grade 4)
A book or chart that helps people identify plants, animals or rocks outdoors, often with pictures and keys.
Grade 4 Life Science: Classification, Lesson 1.4 (grade 4) · Grade 4 Life Science: Classification, Lesson 4.4 (grade 4) · Grade 4 Life Science: Classification, Lesson 8.1 (grade 4)
field interviewEnglish
An interview done at the place where a person works, so you can see the tools and the ground they talk about.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.4 (grade 8)
An interview done at the place where a person works, so you can see the tools and the ground they talk about.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.4 (grade 8)
field kitEnglish
A small set of tools a scientist carries outdoors to observe and test things right where they are found.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.2 (grade 3)
A small set of tools a scientist carries outdoors to observe and test things right where they are found.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.2 (grade 3)
field notebookEnglish
A notebook a scientist carries outdoors to write, measure and sketch what they find, right where they find it.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 8.1 (grade 3) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.2 (grade 8) · High School Geology, Lesson 9.1 (grade 9–12)
A notebook a scientist carries outdoors to write, measure and sketch what they find, right where they find it.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 8.1 (grade 3) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.2 (grade 8) · High School Geology, Lesson 9.1 (grade 9–12)
field notesEnglish
Quick notes and sketches a scientist makes outdoors, right where the living things are.
Grade 3 Life Science: Plants and Animals Together, Lesson 9.1 (grade 3) · Grade 4 Life Science: Classification, Lesson 8.2 (grade 4) · Grade 7 Life Science: Cells and Microbes, Lesson 9.1 (grade 7)
Quick notes and sketches a scientist makes outdoors, right where the living things are.
Grade 3 Life Science: Plants and Animals Together, Lesson 9.1 (grade 3) · Grade 4 Life Science: Classification, Lesson 8.2 (grade 4) · Grade 7 Life Science: Cells and Microbes, Lesson 9.1 (grade 7)
field of viewEnglish
The bright circle you see when you look into a microscope. The higher the magnification, the smaller the field of view.
Grade 5 Life Science: The Human Body, Lesson 1.2 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 1.2 (grade 7)
The bright circle you see when you look into a microscope. The higher the magnification, the smaller the field of view.
Grade 5 Life Science: The Human Body, Lesson 1.2 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 1.2 (grade 7)
field reportEnglish
A written account of a place’s geology built on the writer’s own observations, measurements, maps, and samples.
High School Geology, Lesson 9.4 (grade 9–12)
A written account of a place’s geology built on the writer’s own observations, measurements, maps, and samples.
High School Geology, Lesson 9.4 (grade 9–12)
field studyEnglish
A scientific investigation carried out outdoors where living things actually live, rather than in a laboratory.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.4 (grade 8)
A scientific investigation carried out outdoors where living things actually live, rather than in a laboratory.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.4 (grade 8)
field testEnglish
Trying out a tool or guide in real use, outdoors, to see whether it works and what needs fixing.
Grade 4 Life Science: Classification, Lesson 8.4 (grade 4)
Trying out a tool or guide in real use, outdoors, to see whether it works and what needs fixing.
Grade 4 Life Science: Classification, Lesson 8.4 (grade 4)
field tripEnglish
A trip outside to look at real things right where they are.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.1 (grade 1)
A trip outside to look at real things right where they are.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.1 (grade 1)
figure captionEnglish
The sentence or two under a map, graph or photo that says what it shows, in what units, and where it came from.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.4 (grade 8)
The sentence or two under a map, graph or photo that says what it shows, in what units, and where it came from.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.4 (grade 8)
filamentEnglish
A simple hair-like structure with no rachis or vane. Dark filaments on some dinosaur fossils are read by most paleontologists as simple feathers and by some ornithologists as collagen fibers from skin.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.4 (grade 7) · Grade 3 Engineering & Physics, Lesson 4.1 (grade 3) · Grade 4 Engineering & Physics, Lesson 4.3 (grade 4) · +3 more
A simple hair-like structure with no rachis or vane. Dark filaments on some dinosaur fossils are read by most paleontologists as simple feathers and by some ornithologists as collagen fibers from skin.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.4 (grade 7) · Grade 3 Engineering & Physics, Lesson 4.1 (grade 3) · Grade 4 Engineering & Physics, Lesson 4.3 (grade 4) · +3 more
finEnglish
A thin flap on a fish’s body. Fins push, steer and keep the fish steady in the water.
Kindergarten Life Science: God Made the Animals, Lesson 2.3 (grade K)
A thin flap on a fish’s body. Fins push, steer and keep the fish steady in the water.
Kindergarten Life Science: God Made the Animals, Lesson 2.3 (grade K)
fine-tuningEnglish
The observation that many features of nature, from the laws of physics to Earth’s place near the sun, fall within narrow ranges that life requires.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.4 (grade 8)
The observation that many features of nature, from the laws of physics to Earth’s place near the sun, fall within narrow ranges that life requires.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.4 (grade 8)
fingerprintEnglish
The tiny lines on the tip of your finger. Your fingerprints are yours alone.
Kindergarten Life Science: God Made the Animals, Lesson 6.1 (grade K)
The tiny lines on the tip of your finger. Your fingerprints are yours alone.
Kindergarten Life Science: God Made the Animals, Lesson 6.1 (grade K)
firnEnglish
Old snow that has packed down but not yet turned into solid glacier ice; the top 60 to 100 m of an ice sheet.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.4 (grade 7) · High School Geology, Lesson 3.3 (grade 9–12)
Old snow that has packed down but not yet turned into solid glacier ice; the top 60 to 100 m of an ice sheet.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.4 (grade 7) · High School Geology, Lesson 3.3 (grade 9–12)
first aidEnglish
The first help given to someone who is hurt or suddenly sick, before a doctor or nurse arrives or before they go to get medical care.
Grade 5 Life Science: The Human Body, Lesson 8.4 (grade 5)
The first help given to someone who is hurt or suddenly sick, before a doctor or nurse arrives or before they go to get medical care.
Grade 5 Life Science: The Human Body, Lesson 8.4 (grade 5)
fixed action patternEnglish
A chain of instinctive steps that, once started by a trigger, runs in the same order every time until it is finished.
Grade 6 Life Science: Animal Design and Behavior, Lesson 5.1 (grade 6)
A chain of instinctive steps that, once started by a trigger, runs in the same order every time until it is finished.
Grade 6 Life Science: Animal Design and Behavior, Lesson 5.1 (grade 6)
fizz testEnglish
Putting a drop of acid, such as vinegar, on a mineral. Calcite fizzes with tiny bubbles; quartz, feldspar and mica do not.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.4 (grade 3)
Putting a drop of acid, such as vinegar, on a mineral. Calcite fizzes with tiny bubbles; quartz, feldspar and mica do not.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.4 (grade 3)
flagellumEnglish
A long, whip-like structure that a cell lashes to swim. Euglena has one (plural: flagella).
Grade 7 Life Science: Cells and Microbes, Lesson 1.4 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.3 (grade 8)
A long, whip-like structure that a cell lashes to swim. Euglena has one (plural: flagella).
Grade 7 Life Science: Cells and Microbes, Lesson 1.4 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.3 (grade 8)
flagellum (plural: flagella)English
A long, whip-like tail that some cells spin or lash to swim.
Grade 7 Life Science: Cells and Microbes, Lesson 3.1 (grade 7)
A long, whip-like tail that some cells spin or lash to swim.
Grade 7 Life Science: Cells and Microbes, Lesson 3.1 (grade 7)
flash floodEnglish
A flood that rises very fast, within minutes or a few hours, often after very heavy rain or a dam break.
Grade 4 Earth Science: Weather and Water, Lesson 6.1 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 9.3 (grade 4)
A flood that rises very fast, within minutes or a few hours, often after very heavy rain or a dam break.
Grade 4 Earth Science: Weather and Water, Lesson 6.1 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 9.3 (grade 4)
flash-to-bangEnglish
Counting the seconds from a lightning flash to its thunder to estimate how far away the lightning struck.
Grade 4 Earth Science: Weather and Water, Lesson 9.3 (grade 4)
Counting the seconds from a lightning flash to its thunder to estimate how far away the lightning struck.
Grade 4 Earth Science: Weather and Water, Lesson 9.3 (grade 4)
flexibleEnglish
Able to bend a little without breaking.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.3 (grade 2) · Explore Travel and Faraway Places, Stop 2.4 (Ages 7–9)
Able to bend a little without breaking.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.3 (grade 2) · Explore Travel and Faraway Places, Stop 2.4 (Ages 7–9)
flippersEnglish
Flat, paddle-shaped legs that sea turtles use to swim.
Grade 2 Life Science: Animal Families, Lesson 3.4 (grade 2)
Flat, paddle-shaped legs that sea turtles use to swim.
Grade 2 Life Science: Animal Families, Lesson 3.4 (grade 2)
Flood geologyEnglish
The study of the rock record in light of the global Flood of Genesis 6 to 9, which young-earth geologists hold laid down much of the fossil-bearing sedimentary rock rapidly within about a year and the centuries after.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.1 (grade 8) · High School Geology, Lesson 6.2 (grade 9–12)
The study of the rock record in light of the global Flood of Genesis 6 to 9, which young-earth geologists hold laid down much of the fossil-bearing sedimentary rock rapidly within about a year and the centuries after.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.1 (grade 8) · High School Geology, Lesson 6.2 (grade 9–12)
flood traditionEnglish
A story of a great flood handed down by a people; hundreds have been recorded from every inhabited continent. The Babylonian one on the Gilgamesh tablets is the most famous.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.4 (grade 6)
A story of a great flood handed down by a people; hundreds have been recorded from every inhabited continent. The Babylonian one on the Gilgamesh tablets is the most famous.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.4 (grade 6)
flood ventEnglish
An opening in the lower wall of a building that lets flood water flow in and out, so the water does not push the walls over.
Grade 4 Earth Science: Weather and Water, Lesson 6.4 (grade 4)
An opening in the lower wall of a building that lets flood water flow in and out, so the water does not push the walls over.
Grade 4 Earth Science: Weather and Water, Lesson 6.4 (grade 4)
floodplainEnglish
The flat land beside a river that the river covers when it floods.
Grade 4 Earth Science: Weather and Water, Lesson 6.2 (grade 4) · Grade 6 Earth Science: The Dynamic Earth, Lesson 9.3 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 9.3 (grade 7) · +3 more
The flat land beside a river that the river covers when it floods.
Grade 4 Earth Science: Weather and Water, Lesson 6.2 (grade 4) · Grade 6 Earth Science: The Dynamic Earth, Lesson 9.3 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 9.3 (grade 7) · +3 more
floodwayEnglish
A path engineers leave open on purpose so extra flood water can leave the main river and flow somewhere safer.
Grade 4 Earth Science: Weather and Water, Lesson 6.2 (grade 4)
A path engineers leave open on purpose so extra flood water can leave the main river and flow somewhere safer.
Grade 4 Earth Science: Weather and Water, Lesson 6.2 (grade 4)
floor planEnglish
A scale map of the museum’s halls. Its scale bar lets you turn centimeters on the map into meters in the building.
Grade 7 Earth Science: Earth History and the Flood, Lesson 8.1 (grade 7) · Architecture & Civil Engineering, Lesson 2.2 (grade 9–12) · Explore Hospitality and Home · Ranger, Stop 4.6 (Ages 10–13) · +2 more
A scale map of the museum’s halls. Its scale bar lets you turn centimeters on the map into meters in the building.
Grade 7 Earth Science: Earth History and the Flood, Lesson 8.1 (grade 7) · Architecture & Civil Engineering, Lesson 2.2 (grade 9–12) · Explore Hospitality and Home · Ranger, Stop 4.6 (Ages 10–13) · +2 more
flow modelEnglish
A mathematical model of how ice thins and spreads as it is squeezed under new snow, used to assign ages where layers can no longer be counted.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.4 (grade 7)
A mathematical model of how ice thins and spreads as it is squeezed under new snow, used to assign ages where layers can no longer be counted.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.4 (grade 7)
flow rateEnglish
How much water moves per unit of time, measured here in liters per minute (L/min).
Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.2 (grade 8) · Grade 8 Engineering & Physics, Lesson 5.2 (grade 8)
How much water moves per unit of time, measured here in liters per minute (L/min).
Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.2 (grade 8) · Grade 8 Engineering & Physics, Lesson 5.2 (grade 8)
flowering plantEnglish
A plant that makes flowers and grows its seeds inside a fruit. Scientists also call flowering plants angiosperms. They are the largest group of plants.
Grade 4 Life Science: Classification, Lesson 6.3 (grade 4)
A plant that makes flowers and grows its seeds inside a fruit. Scientists also call flowering plants angiosperms. They are the largest group of plants.
Grade 4 Life Science: Classification, Lesson 6.3 (grade 4)
flumeEnglish
A long channel through which water flows at a controlled speed, used to study how currents move and lay down sediment.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.3 (grade 7) · High School Geology, Lesson 9.3 (grade 9–12)
A long channel through which water flows at a controlled speed, used to study how currents move and lay down sediment.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.3 (grade 7) · High School Geology, Lesson 9.3 (grade 9–12)
flybyEnglish
A trip in which a probe passes close by a planet or moon and takes pictures without stopping or landing.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.4 (grade 5)
A trip in which a probe passes close by a planet or moon and takes pictures without stopping or landing.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.4 (grade 5)
focal lengthEnglish
The distance from a lens to the point where it brings light from a faraway object into focus.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.1 (grade 5) · Physics, Lesson 9.4 (grade 11–12)
The distance from a lens to the point where it brings light from a faraway object into focus.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.1 (grade 5) · Physics, Lesson 9.4 (grade 11–12)
focus (plural: foci)English
One of the two special points inside an ellipse. In a planet’s orbit, the Sun sits at one focus and the other is empty.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.2 (grade 5)
One of the two special points inside an ellipse. In a planet’s orbit, the Sun sits at one focus and the other is empty.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.2 (grade 5)
fogEnglish
A cloud that forms at ground level when air near the ground cools to its dew point.
Grade 4 Earth Science: Weather and Water, Lesson 1.3 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 3.3 (grade 4)
A cloud that forms at ground level when air near the ground cools to its dew point.
Grade 4 Earth Science: Weather and Water, Lesson 1.3 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 3.3 (grade 4)
folded mountainsEnglish
Mountains made when layers of rock are pushed from the sides and bent up high.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.2 (grade 2)
Mountains made when layers of rock are pushed from the sides and bent up high.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.2 (grade 2)
foliationEnglish
The layered or striped texture of a metamorphic rock produced when flat or elongated minerals line up across the direction of pressure.
High School Geology, Lesson 1.4 (grade 9–12)
The layered or striped texture of a metamorphic rock produced when flat or elongated minerals line up across the direction of pressure.
High School Geology, Lesson 1.4 (grade 9–12)
food chainEnglish
A chain of who eats whom. Tiny green plants are eaten by tiny animals, and those are eaten by bigger animals.
Grade 1 Life Science: Animal Homes and Habits, Lesson 2.4 (grade 1) · Grade 3 Life Science: Plants and Animals Together, Lesson 4.1 (grade 3) · Grade 7 Life Science: Cells and Microbes, Lesson 8.3 (grade 7)
A chain of who eats whom. Tiny green plants are eaten by tiny animals, and those are eaten by bigger animals.
Grade 1 Life Science: Animal Homes and Habits, Lesson 2.4 (grade 1) · Grade 3 Life Science: Plants and Animals Together, Lesson 4.1 (grade 3) · Grade 7 Life Science: Cells and Microbes, Lesson 8.3 (grade 7)
food storeEnglish
The two fat halves inside a bean. They are the packed lunch for the baby plant.
Kindergarten Life Science: God Made the Animals, Lesson 5.1 (grade K)
The two fat halves inside a bean. They are the packed lunch for the baby plant.
Kindergarten Life Science: God Made the Animals, Lesson 5.1 (grade K)
foragerEnglish
An older worker bee that flies out of the hive to collect nectar, pollen, water or plant resin.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.1 (grade 6)
An older worker bee that flies out of the hive to collect nectar, pollen, water or plant resin.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.1 (grade 6)
forceEnglish
A push or a pull. Gravity is a pulling force.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.3 (grade 5) · Grade 3 Engineering & Physics, Lesson 1.1 (grade 3) · Grade 5 Engineering & Physics, Lesson 1.2 (grade 5) · +3 more
A push or a pull. Gravity is a pulling force.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.3 (grade 5) · Grade 3 Engineering & Physics, Lesson 1.1 (grade 3) · Grade 5 Engineering & Physics, Lesson 1.2 (grade 5) · +3 more
forecast verificationEnglish
Checking a forecast against what really happened and measuring the error, so that forecasters can learn and improve.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.4 (grade 8)
Checking a forecast against what really happened and measuring the error, so that forecasters can learn and improve.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.4 (grade 8)
forest floorEnglish
The dark, damp ground of the forest, covered with fallen leaves. Very little sunlight reaches it.
Grade 3 Life Science: Plants and Animals Together, Lesson 5.2 (grade 3)
The dark, damp ground of the forest, covered with fallen leaves. Very little sunlight reaches it.
Grade 3 Life Science: Plants and Animals Together, Lesson 5.2 (grade 3)
forgetting curveEnglish
A graph showing how quickly we forget something after learning it: fast at first, then more slowly.
Grade 5 Life Science: The Human Body, Lesson 6.3 (grade 5)
A graph showing how quickly we forget something after learning it: fast at first, then more slowly.
Grade 5 Life Science: The Human Body, Lesson 6.3 (grade 5)
formationEnglish
A body of rock thick and distinct enough to be mapped and given a name, such as the Coconino Sandstone.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.1 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.4 (grade 8) · Explore Dinosaurs · Expert, Stop 4.5 (Ages 14+) · +3 more
A body of rock thick and distinct enough to be mapped and given a name, such as the Coconino Sandstone.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.1 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.4 (grade 8) · Explore Dinosaurs · Expert, Stop 4.5 (Ages 14+) · +3 more
forming and fillingEnglish
The pattern of Genesis 1: on days 1–3 God forms spaces (light, sky and waters, land), and on days 4–6 He fills them (lights, swimmers and fliers, land animals and man).
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.1 (grade 8)
The pattern of Genesis 1: on days 1–3 God forms spaces (light, sky and waters, land), and on days 4–6 He fills them (lights, swimmers and fliers, land animals and man).
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.1 (grade 8)
fossilEnglish
Part of a living thing, or a mark it made, that has been kept in rock. Bones, shells, teeth and footprints can all become fossils.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.1 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 7.1 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.1 (grade 3) · +3 more
Part of a living thing, or a mark it made, that has been kept in rock. Bones, shells, teeth and footprints can all become fossils.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.1 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 7.1 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.1 (grade 3) · +3 more
fossil fuelEnglish
A fuel such as coal, oil or natural gas that comes from the buried remains of things that once lived.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.3 (grade 3)
A fuel such as coal, oil or natural gas that comes from the buried remains of things that once lived.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.3 (grade 3)
fossil graveyard (bone bed)English
A single rock layer packed with the bones of many animals, often of several kinds, buried together.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.2 (grade 6)
A single rock layer packed with the bones of many animals, often of several kinds, buried together.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.2 (grade 6)
Foucault pendulumEnglish
A long, heavy pendulum whose swing slowly turns as the earth rotates beneath it (say foo-KOH).
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.3 (grade 5)
A long, heavy pendulum whose swing slowly turns as the earth rotates beneath it (say foo-KOH).
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.3 (grade 5)
foundationsEnglish
The strong bottom parts of a building that hold it up. At Philippi the earthquake shook the prison’s foundations.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.4 (grade 2)
The strong bottom parts of a building that hold it up. At Philippi the earthquake shook the prison’s foundations.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.4 (grade 2)
fountains of the great deepEnglish
The first source of Flood water named in Genesis 7:11: water bursting up from beneath the earth’s surface when the deep was “broken up,” which creation geologists read as the crust itself tearing open.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.4 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 4.1 (grade 7)
The first source of Flood water named in Genesis 7:11: water bursting up from beneath the earth’s surface when the deep was “broken up,” which creation geologists read as the crust itself tearing open.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.4 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 4.1 (grade 7)
fractionEnglish
One of the groups of molecules collected from a distillation tower, such as gases, gasoline, kerosene and jet fuel, diesel, lubricating oil and residue.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.4 (grade 8) · Explore Horses and Ponies · Expert, Stop 3.8 (Ages 14+) · Explore Hospitality and Home, Stop 1.2 (Ages 7–9) · +1 more
One of the groups of molecules collected from a distillation tower, such as gases, gasoline, kerosene and jet fuel, diesel, lubricating oil and residue.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.4 (grade 8) · Explore Horses and Ponies · Expert, Stop 3.8 (Ages 14+) · Explore Hospitality and Home, Stop 1.2 (Ages 7–9) · +1 more
fractional distillationEnglish
Separating a mixture by heating it so that its parts boil off at different temperatures. In a refinery tower, the smallest molecules rise highest and the heaviest stay at the bottom.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.4 (grade 8)
Separating a mixture by heating it so that its parts boil off at different temperatures. In a refinery tower, the smallest molecules rise highest and the heaviest stay at the bottom.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.4 (grade 8)
fractureEnglish
A rough or curved break that does not follow flat surfaces. Quartz breaks with curved, shell-shaped surfaces, like broken glass.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.4 (grade 3)
A rough or curved break that does not follow flat surfaces. Quartz breaks with curved, shell-shaped surfaces, like broken glass.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.4 (grade 3)
frameworkEnglish
The set of starting assumptions a person brings to the evidence, such as “rates have always been as they are now” or “Genesis 6 to 9 is history.” Two people with the same bones and different frameworks will write different story lines.
Grade 7 Earth Science: Earth History and the Flood, Lesson 8.2 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 8.3 (grade 7)
The set of starting assumptions a person brings to the evidence, such as “rates have always been as they are now” or “Genesis 6 to 9 is history.” Two people with the same bones and different frameworks will write different story lines.
Grade 7 Earth Science: Earth History and the Flood, Lesson 8.2 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 8.3 (grade 7)
framework viewEnglish
The reading in which the six days are a literary pattern (days 1 to 3 form realms, days 4 to 6 fill them) rather than a timeline, so Genesis 1 is silent on how long creation took.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.2 (grade 8)
The reading in which the six days are a literary pattern (days 1 to 3 form realms, days 4 to 6 fill them) rather than a timeline, so Genesis 1 is silent on how long creation took.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.2 (grade 8)
freezingEnglish
Cold enough for water to turn into ice.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 8.1 (grade 1)
Cold enough for water to turn into ice.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 8.1 (grade 1)
frogletEnglish
A young frog that has four legs and lungs but still has a short tail.
Grade 2 Life Science: Animal Families, Lesson 4.2 (grade 2) · Grade 2 Life Science: Animal Families, Lesson 8.3 (grade 2)
A young frog that has four legs and lungs but still has a short tail.
Grade 2 Life Science: Animal Families, Lesson 4.2 (grade 2) · Grade 2 Life Science: Animal Families, Lesson 8.3 (grade 2)
frondEnglish
The leaf of a fern. A young frond comes up rolled tight and is called a fiddlehead.
Grade 4 Life Science: Classification, Lesson 6.1 (grade 4)
The leaf of a fern. A young frond comes up rolled tight and is called a fiddlehead.
Grade 4 Life Science: Classification, Lesson 6.1 (grade 4)
frontEnglish
The boundary where two different air masses meet.
Grade 4 Earth Science: Weather and Water, Lesson 5.3 (grade 4)
The boundary where two different air masses meet.
Grade 4 Earth Science: Weather and Water, Lesson 5.3 (grade 4)
frostEnglish
Ice crystals that form on a surface when it cools to a dew point that is below freezing, 0°C (32°F).
Grade 4 Earth Science: Weather and Water, Lesson 3.3 (grade 4) · Grade 1 Gardening & Animals, Lesson 7.2 (grade 1) · Grade 2 Gardening & Animals, Lesson 1.2 (grade 2) · +3 more
Ice crystals that form on a surface when it cools to a dew point that is below freezing, 0°C (32°F).
Grade 4 Earth Science: Weather and Water, Lesson 3.3 (grade 4) · Grade 1 Gardening & Animals, Lesson 7.2 (grade 1) · Grade 2 Gardening & Animals, Lesson 1.2 (grade 2) · +3 more
fruiting bodyEnglish
The part of a fungus that grows up to make and release spores. A mushroom is a fruiting body.
Grade 7 Life Science: Cells and Microbes, Lesson 6.1 (grade 7)
The part of a fungus that grows up to make and release spores. A mushroom is a fruiting body.
Grade 7 Life Science: Cells and Microbes, Lesson 6.1 (grade 7)
full moonEnglish
When we see the whole round face of the moon lit up, like a bright plate.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.1 (grade 1) · Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.4 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 5.3 (grade K)
When we see the whole round face of the moon lit up, like a bright plate.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.1 (grade 1) · Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.4 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 5.3 (grade K)
fungus gardenEnglish
A spongy mass of chewed leaves inside a leafcutter ant nest, on which the ants grow the fungus they eat.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.4 (grade 6)
A spongy mass of chewed leaves inside a leafcutter ant nest, on which the ants grow the fungus they eat.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.4 (grade 6)
fungus (plural fungi)English
A living thing whose cells have walls made of chitin and that cannot make its own food; it digests food outside its body and absorbs it. Mushrooms, molds and yeasts are fungi.
Grade 7 Life Science: Cells and Microbes, Lesson 6.1 (grade 7)
A living thing whose cells have walls made of chitin and that cannot make its own food; it digests food outside its body and absorbs it. Mushrooms, molds and yeasts are fungi.
Grade 7 Life Science: Cells and Microbes, Lesson 6.1 (grade 7)
funnel cloudEnglish
A spinning, cone-shaped cloud hanging from a storm that has not touched the ground. If it touches down, it is a tornado.
Grade 4 Earth Science: Weather and Water, Lesson 4.2 (grade 4)
A spinning, cone-shaped cloud hanging from a storm that has not touched the ground. If it touches down, it is a tornado.
Grade 4 Earth Science: Weather and Water, Lesson 4.2 (grade 4)
fuseEnglish
To grow together into one piece, as several baby bones do to form one adult bone.
Grade 5 Life Science: The Human Body, Lesson 2.2 (grade 5)
To grow together into one piece, as several baby bones do to form one adult bone.
Grade 5 Life Science: The Human Body, Lesson 2.2 (grade 5)
G
gallons per minute (gpm)English
The unit American drillers use for a well’s yield; one gallon is 3.785 liters, so 10 gpm is about 38 liters per minute.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.3 (grade 8)
The unit American drillers use for a well’s yield; one gallon is 3.785 liters, so 10 gpm is about 38 liters per minute.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.3 (grade 8)
game animalEnglish
A wild animal that may be legally hunted for food or sport under state or federal rules, such as deer, elk, wild turkey, ducks and rabbits.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 7.4 (grade 8)
A wild animal that may be legally hunted for food or sport under state or federal rules, such as deer, elk, wild turkey, ducks and rabbits.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 7.4 (grade 8)
game wardenEnglish
A law officer, also called a conservation officer, who enforces hunting, fishing and wildlife laws, helps the public and protects wild animals and the people who enjoy them.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.2 (grade 8)
A law officer, also called a conservation officer, who enforces hunting, fishing and wildlife laws, helps the public and protects wild animals and the people who enjoy them.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.2 (grade 8)
gameteEnglish
A reproductive cell (pollen or egg cell in plants; sperm or egg cell in animals) that carries only one allele of each gene.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.3 (grade 8)
A reproductive cell (pollen or egg cell in plants; sperm or egg cell in animals) that carries only one allele of each gene.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.3 (grade 8)
ganglionEnglish
A small cluster of nerve cells that acts as a control center. Insects have a chain of ganglia; the ones in the thorax control the legs and wings.
Grade 6 Life Science: Animal Design and Behavior, Lesson 5.1 (grade 6)
A small cluster of nerve cells that acts as a control center. Insects have a chain of ganglia; the ones in the thorax control the legs and wings.
Grade 6 Life Science: Animal Design and Behavior, Lesson 5.1 (grade 6)
gap viewEnglish
The reading in which Genesis 1:1 describes an original creation, a long gap of time (holding most of the rock record) falls before Genesis 1:2, and the six days that follow are ordinary days of remaking the earth.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.2 (grade 8)
The reading in which Genesis 1:1 describes an original creation, a long gap of time (holding most of the rock record) falls before Genesis 1:2, and the six days that follow are ordinary days of remaking the earth.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.2 (grade 8)
gastric juiceEnglish
The strong, acid juice made by the lining of the stomach that helps break down food, especially meat and other proteins.
Grade 5 Life Science: The Human Body, Lesson 5.1 (grade 5)
The strong, acid juice made by the lining of the stomach that helps break down food, especially meat and other proteins.
Grade 5 Life Science: The Human Body, Lesson 5.1 (grade 5)
gastropodEnglish
The mollusk group that includes snails and slugs. The name means “stomach-foot,” because the animal seems to crawl on its belly.
Grade 4 Life Science: Classification, Lesson 3.3 (grade 4)
The mollusk group that includes snails and slugs. The name means “stomach-foot,” because the animal seems to crawl on its belly.
Grade 4 Life Science: Classification, Lesson 3.3 (grade 4)
gemEnglish
A stone that is beautiful, rare and tough enough to be cut, polished and worn. Most gems are minerals, such as emerald, sapphire and amethyst.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.1 (grade 3)
A stone that is beautiful, rare and tough enough to be cut, polished and worn. Most gems are minerals, such as emerald, sapphire and amethyst.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.1 (grade 3)
gene knockoutEnglish
An experiment in which scientists disable one gene and watch what the living thing can no longer do. It shows which parts a system needs.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.3 (grade 8)
An experiment in which scientists disable one gene and watch what the living thing can no longer do. It shows which parts a system needs.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.3 (grade 8)
gene poolEnglish
All the alleles of all the genes in a population. A breed’s gene pool is smaller than that of dogs as a whole.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.2 (grade 8)
All the alleles of all the genes in a population. A breed’s gene pool is smaller than that of dogs as a whole.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.2 (grade 8)
genetic codeEnglish
The set of rules by which the order of bases in DNA and RNA is translated into the order of amino acids in a protein.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.3 (grade 8)
The set of rules by which the order of bases in DNA and RNA is translated into the order of amino acids in a protein.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.3 (grade 8)
genotypeEnglish
The pair of alleles an organism carries for a trait, such as RR, Rr or rr.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.2 (grade 8)
The pair of alleles an organism carries for a trait, such as RR, Rr or rr.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.2 (grade 8)
genusEnglish
A group of closely related species that shares the first part of the Latin name, such as Triceratops.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.1 (grade 7) · Explore Animals · Expert, Stop 6.10 (Ages 14+) · Explore Animals · Ranger, Stop 6.10 (Ages 10–13) · +3 more
A group of closely related species that shares the first part of the Latin name, such as Triceratops.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.1 (grade 7) · Explore Animals · Expert, Stop 6.10 (Ages 14+) · Explore Animals · Ranger, Stop 6.10 (Ages 10–13) · +3 more
geodynamoEnglish
The mainstream explanation that churning liquid iron in the outer core acts like a natural generator, keeping Earth’s electric currents and magnetic field going.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.4 (grade 6)
The mainstream explanation that churning liquid iron in the outer core acts like a natural generator, keeping Earth’s electric currents and magnetic field going.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.4 (grade 6)
geographic information system (GIS)English
Computer software that stores map features together with data about them, so you can display them as layers, ask questions and measure.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.3 (grade 8) · Human Geography, Lesson 1.3 (grade 9–12)
Computer software that stores map features together with data about them, so you can display them as layers, ask questions and measure.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.3 (grade 8) · Human Geography, Lesson 1.3 (grade 9–12)
geologic columnEnglish
A museum word: the ordered stack of all named layer sets (Cambrian, Devonian, Jurassic and so on) pieced together from many places. No single place contains the whole column.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.2 (grade 7)
A museum word: the ordered stack of all named layer sets (Cambrian, Devonian, Jurassic and so on) pieced together from many places. No single place contains the whole column.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.2 (grade 7)
geologic mapEnglish
A map that colors the land by the kind of rock found just under the soil, with lines where one rock unit meets the next.
Grade 7 Earth Science: Earth History and the Flood, Lesson 9.2 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.1 (grade 8)
A map that colors the land by the kind of rock found just under the soil, with lines where one rock unit meets the next.
Grade 7 Earth Science: Earth History and the Flood, Lesson 9.2 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.1 (grade 8)
geologic time scaleEnglish
The chart that divides the textbook’s 4.5 billion years into eons, eras and periods (such as Cambrian, Jurassic, Cretaceous), with ages in millions of years; the period names are museum words you will meet on signs.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.3 (grade 8)
The chart that divides the textbook’s 4.5 billion years into eons, eras and periods (such as Cambrian, Jurassic, Cretaceous), with ages in millions of years; the period names are museum words you will meet on signs.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.3 (grade 8)
geologistEnglish
A scientist who studies rocks and the ground.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.1 (grade K) · Explore Dinosaurs, Stop 2.2 (Ages 7–9)
A scientist who studies rocks and the ground.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.1 (grade K) · Explore Dinosaurs, Stop 2.2 (Ages 7–9)
germ theory of diseaseEnglish
The scientific theory that many diseases are caused by microbes (germs) that pass from one living thing to another.
Grade 7 Life Science: Cells and Microbes, Lesson 4.2 (grade 7)
The scientific theory that many diseases are caused by microbes (germs) that pass from one living thing to another.
Grade 7 Life Science: Cells and Microbes, Lesson 4.2 (grade 7)
giant current rippleEnglish
A ripple mark shaped like the ones in a stream bed but as tall as a house, left by deep, fast floodwater.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.1 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 4.4 (grade 7)
A ripple mark shaped like the ones in a stream bed but as tall as a house, left by deep, fast floodwater.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.1 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 4.4 (grade 7)
gibbousEnglish
A fat moon that is more than half lit but not yet full. Say it “GIB-us.”
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.2 (grade 1) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.2 (grade 5)
A fat moon that is more than half lit but not yet full. Say it “GIB-us.”
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.2 (grade 1) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.2 (grade 5)
gill coverEnglish
A thin flap on the side of a fish’s head that covers and protects the gills. It opens to let water out.
Grade 2 Life Science: Animal Families, Lesson 5.1 (grade 2)
A thin flap on the side of a fish’s head that covers and protects the gills. It opens to let water out.
Grade 2 Life Science: Animal Families, Lesson 5.1 (grade 2)
gill filamentEnglish
One of the many thin, comb-like strands that hang from each gill arch. Each filament is covered with even thinner plates called lamellae.
Grade 7 Life Science: Cells and Microbes, Lesson 7.1 (grade 7)
One of the many thin, comb-like strands that hang from each gill arch. Each filament is covered with even thinner plates called lamellae.
Grade 7 Life Science: Cells and Microbes, Lesson 7.1 (grade 7)
gill slitsEnglish
Openings in a row on each side of a shark’s head where water flows out over its gills. Most sharks have five on each side.
Grade 2 Life Science: Animal Families, Lesson 5.2 (grade 2)
Openings in a row on each side of a shark’s head where water flows out over its gills. Most sharks have five on each side.
Grade 2 Life Science: Animal Families, Lesson 5.2 (grade 2)
gizzardEnglish
A strong, muscular part of a bird’s stomach. In an owl it squeezes the fur and bones into a pellet.
Grade 3 Life Science: Plants and Animals Together, Lesson 4.3 (grade 3) · Grade 7 Life Science: Cells and Microbes, Lesson 8.1 (grade 7) · Grade 7 Life Science: Cells and Microbes, Lesson 8.3 (grade 7)
A strong, muscular part of a bird’s stomach. In an owl it squeezes the fur and bones into a pellet.
Grade 3 Life Science: Plants and Animals Together, Lesson 4.3 (grade 3) · Grade 7 Life Science: Cells and Microbes, Lesson 8.1 (grade 7) · Grade 7 Life Science: Cells and Microbes, Lesson 8.3 (grade 7)
glacial striationsEnglish
Long parallel scratches cut into bedrock by stones dragged along under a moving glacier. They show which way the ice moved.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.2 (grade 6)
Long parallel scratches cut into bedrock by stones dragged along under a moving glacier. They show which way the ice moved.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.2 (grade 6)
glacierEnglish
A huge field of ice, made from snow packed down hard, that moves slowly downhill like a very slow river.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.1 (grade 2) · Grade 7 Earth Science: Earth History and the Flood, Lesson 5.1 (grade 7) · Explore Travel and Faraway Places · Expert, Stop 4.5 (Ages 14+) · +3 more
A huge field of ice, made from snow packed down hard, that moves slowly downhill like a very slow river.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.1 (grade 2) · Grade 7 Earth Science: Earth History and the Flood, Lesson 5.1 (grade 7) · Explore Travel and Faraway Places · Expert, Stop 4.5 (Ages 14+) · +3 more
global floodEnglish
A flood that covers all the land on earth at once, as Genesis 7:19 describes: “all the high hills, that were under the whole heaven, were covered.” A local flood covers one valley or region.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.4 (grade 6) · Explore Dinosaurs · Expert, Stop 4.4 (Ages 14+)
A flood that covers all the land on earth at once, as Genesis 7:19 describes: “all the high hills, that were under the whole heaven, were covered.” A local flood covers one valley or region.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.4 (grade 6) · Explore Dinosaurs · Expert, Stop 4.4 (Ages 14+)
glossaryEnglish
A short dictionary at the back of a book that explains the special words used in it.
Grade 4 Life Science: Classification, Lesson 8.4 (grade 4)
A short dictionary at the back of a book that explains the special words used in it.
Grade 4 Life Science: Classification, Lesson 8.4 (grade 4)
glossopetraeEnglish
“tongue stones,” the triangular fossils found in Mediterranean rock that Steno identified in 1667 as the teeth of sharks.
High School Geology, Lesson 5.1 (grade 9–12) · High School Geology, Lesson 8.3 (grade 9–12)
“tongue stones,” the triangular fossils found in Mediterranean rock that Steno identified in 1667 as the teeth of sharks.
High School Geology, Lesson 5.1 (grade 9–12) · High School Geology, Lesson 8.3 (grade 9–12)
GlossopterisEnglish
A fossil seed plant with tongue-shaped leaves found in South America, Africa, India, Australia and Antarctica.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.2 (grade 6)
A fossil seed plant with tongue-shaped leaves found in South America, Africa, India, Australia and Antarctica.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.2 (grade 6)
glow (incandescence)English
Light given off by something because it is very hot, like a toaster coil or the surface of a star.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.3 (grade 5)
Light given off by something because it is very hot, like a toaster coil or the surface of a star.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.3 (grade 5)
gneissEnglish
A hard metamorphic rock (say “nice”) with light and dark stripes, or bands, of minerals. Granite can become gneiss.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.1 (grade 3)
A hard metamorphic rock (say “nice”) with light and dark stripes, or bands, of minerals. Granite can become gneiss.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.1 (grade 3)
gnomonEnglish
The part of a sundial that casts the shadow (say NO-mon). On a good sundial its edge points toward the North Star.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.2 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.1 (grade 5)
The part of a sundial that casts the shadow (say NO-mon). On a good sundial its edge points toward the North Star.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.2 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.1 (grade 5)
goldfishEnglish
A small orange or gold pet fish that first came from China, long ago.
Kindergarten Life Science: God Made the Animals, Lesson 2.3 (grade K)
A small orange or gold pet fish that first came from China, long ago.
Kindergarten Life Science: God Made the Animals, Lesson 2.3 (grade K)
good soilEnglish
Dark, crumbly soil that holds water and has plant food in it, so plants grow well.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.4 (grade K)
Dark, crumbly soil that holds water and has plant food in it, so plants grow well.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.4 (grade K)
gorgeEnglish
A deep, steep-walled valley cut by a river. The Niagara Gorge is the 11 km trench the falls left behind as they retreated.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.1 (grade 6) · Grade 5 Geography: Explorers, Navigators and Missionaries, Lesson 6.2 (grade 5) · Geography and History: Why Borders Fall Where They Do, Lesson 2.2 (grade 9–12)
A deep, steep-walled valley cut by a river. The Niagara Gorge is the 11 km trench the falls left behind as they retreated.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.1 (grade 6) · Grade 5 Geography: Explorers, Navigators and Missionaries, Lesson 6.2 (grade 5) · Geography and History: Why Borders Fall Where They Do, Lesson 2.2 (grade 9–12)
graded bedEnglish
A single layer in which grains are coarse at the bottom and finer toward the top, because large grains settle first.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.2 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 9.3 (grade 7)
A single layer in which grains are coarse at the bottom and finer toward the top, because large grains settle first.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.2 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 9.3 (grade 7)
graded beddingEnglish
A layer in which grain size changes from bottom to top, usually coarse at the base and fine at the top, formed as a current slows.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.3 (grade 7)
A layer in which grain size changes from bottom to top, usually coarse at the base and fine at the top, formed as a current slows.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.3 (grade 7)
gradientEnglish
The steepness of a slope, found by dividing the rise in elevation by the horizontal distance (rise over run), often written as a percent.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.2 (grade 8) · Grade 5 Engineering & Physics, Lesson 5.1 (grade 5) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 4.2 (grade 6) · +2 more
The steepness of a slope, found by dividing the rise in elevation by the horizontal distance (rise over run), often written as a percent.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.2 (grade 8) · Grade 5 Engineering & Physics, Lesson 5.1 (grade 5) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 4.2 (grade 6) · +2 more
grain sizeEnglish
The diameter of sediment particles: clay is finer than 0.004 mm, silt runs from 0.004 to 0.0625 mm, sand from 0.0625 to 2 mm, and gravel is coarser than 2 mm.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.3 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 9.1 (grade 7) · Architecture & Civil Engineering, Lesson 8.1 (grade 9–12)
The diameter of sediment particles: clay is finer than 0.004 mm, silt runs from 0.004 to 0.0625 mm, sand from 0.0625 to 2 mm, and gravel is coarser than 2 mm.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.3 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 9.1 (grade 7) · Architecture & Civil Engineering, Lesson 8.1 (grade 9–12)
Gram stainEnglish
A staining method invented by Hans Christian Gram in 1884. Gram-positive bacteria, with thick cell walls, stay purple; Gram-negative bacteria, with thin walls and an outer membrane, lose the purple and are counterstained pink.
Grade 7 Life Science: Cells and Microbes, Lesson 3.1 (grade 7)
A staining method invented by Hans Christian Gram in 1884. Gram-positive bacteria, with thick cell walls, stay purple; Gram-negative bacteria, with thin walls and an outer membrane, lose the purple and are counterstained pink.
Grade 7 Life Science: Cells and Microbes, Lesson 3.1 (grade 7)
graniteEnglish
A speckled rock made mostly of quartz and feldspar, often with flakes of mica.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.4 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.2 (grade 3)
A speckled rock made mostly of quartz and feldspar, often with flakes of mica.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.4 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.2 (grade 3)
gravityEnglish
The pull that holds us down to the ground. The moon’s pull is much weaker than the earth’s, so things feel much lighter there.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.3 (grade 1) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.4 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.3 (grade 5) · +3 more
The pull that holds us down to the ground. The moon’s pull is much weaker than the earth’s, so things feel much lighter there.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.3 (grade 1) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.4 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.3 (grade 5) · +3 more
Great UnconformityEnglish
The surface in the Grand Canyon where flat Tapeats Sandstone rests on tilted or crystalline rocks below; named by John Wesley Powell.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.1 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.4 (grade 8) · High School Geology, Lesson 6.3 (grade 9–12)
The surface in the Grand Canyon where flat Tapeats Sandstone rests on tilted or crystalline rocks below; named by John Wesley Powell.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.1 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.4 (grade 8) · High School Geology, Lesson 6.3 (grade 9–12)
Gregorian calendarEnglish
The calendar set up by Pope Gregory XIII in 1582 and used for everyday dates around the world today. It skips three leap days every 400 years.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.3 (grade 5)
The calendar set up by Pope Gregory XIII in 1582 and used for everyday dates around the world today. It skips three leap days every 400 years.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.3 (grade 5)
grindEnglish
To crush something into tiny bits, the way a mill crushes grain into flour.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.3 (grade 1)
To crush something into tiny bits, the way a mill crushes grain into flour.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.3 (grade 1)
groundwaterEnglish
Water that fills the tiny spaces between grains of soil, sand and gravel and the cracks in rock below the ground.
Grade 4 Earth Science: Weather and Water, Lesson 1.4 (grade 4) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.1 (grade 8) · Grade 2 Engineering & Physics, Lesson 5.2 (grade 2) · +1 more
Water that fills the tiny spaces between grains of soil, sand and gravel and the cracks in rock below the ground.
Grade 4 Earth Science: Weather and Water, Lesson 1.4 (grade 4) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.1 (grade 8) · Grade 2 Engineering & Physics, Lesson 5.2 (grade 2) · +1 more
Gulf StreamEnglish
A strong, fast, warm ocean current that flows out of the Gulf of Mexico, around Florida, north along the coast of the United States and then northeast across the Atlantic.
Grade 4 Earth Science: Weather and Water, Lesson 7.4 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 7.1 (grade 6)
A strong, fast, warm ocean current that flows out of the Gulf of Mexico, around Florida, north along the coast of the United States and then northeast across the Atlantic.
Grade 4 Earth Science: Weather and Water, Lesson 7.4 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 7.1 (grade 6)
gusherEnglish
A well in which underground pressure shoots oil and gas uncontrolled out of the top. Today it is called a blowout and is prevented with heavy mud and steel valves.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.2 (grade 8)
A well in which underground pressure shoots oil and gas uncontrolled out of the top. Today it is called a blowout and is prevented with heavy mud and steel valves.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.2 (grade 8)
gustEnglish
A sudden, quick push of stronger wind.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.3 (grade 1)
A sudden, quick push of stronger wind.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.3 (grade 1)
gymnospermEnglish
A seed plant whose seeds lie bare on a scale or stalk instead of inside a fruit. The word means “naked seed.” Conifers are gymnosperms.
Grade 4 Life Science: Classification, Lesson 6.2 (grade 4)
A seed plant whose seeds lie bare on a scale or stalk instead of inside a fruit. The word means “naked seed.” Conifers are gymnosperms.
Grade 4 Life Science: Classification, Lesson 6.2 (grade 4)
gyreEnglish
A huge loop of ocean currents that circles an ocean basin. Gyres turn clockwise north of the equator and counterclockwise south of it.
Grade 4 Earth Science: Weather and Water, Lesson 7.2 (grade 4) · Geography and Commerce: Sea Lanes, Straits and Trade Routes, Lesson 2.5 (grade 9–12) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 7.2 (grade 6)
A huge loop of ocean currents that circles an ocean basin. Gyres turn clockwise north of the equator and counterclockwise south of it.
Grade 4 Earth Science: Weather and Water, Lesson 7.2 (grade 4) · Geography and Commerce: Sea Lanes, Straits and Trade Routes, Lesson 2.5 (grade 9–12) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 7.2 (grade 6)
H
habitable zoneEnglish
The range of distances from a star where a planet’s surface could be the right temperature for liquid water.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.4 (grade 8)
The range of distances from a star where a planet’s surface could be the right temperature for liquid water.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.4 (grade 8)
haloEnglish
A ring of light around the sun or moon, made when light bends through the ice crystals of a cirrostratus cloud.
Grade 4 Earth Science: Weather and Water, Lesson 3.2 (grade 4)
A ring of light around the sun or moon, made when light bends through the ice crystals of a cirrostratus cloud.
Grade 4 Earth Science: Weather and Water, Lesson 3.2 (grade 4)
halteresEnglish
Tiny knobbed stalks in true flies that take the place of the hind wings. They beat with the wings and work as balance sensors, telling the fly when it starts to turn.
Grade 6 Life Science: Animal Design and Behavior, Lesson 1.3 (grade 6)
Tiny knobbed stalks in true flies that take the place of the hind wings. They beat with the wings and work as balance sensors, telling the fly when it starts to turn.
Grade 6 Life Science: Animal Design and Behavior, Lesson 1.3 (grade 6)
hand specimenEnglish
A fist-sized rock sample that can be identified with simple tests and a hand lens.
High School Geology, Lesson 9.1 (grade 9–12)
A fist-sized rock sample that can be identified with simple tests and a hand lens.
High School Geology, Lesson 9.1 (grade 9–12)
hanging wall and footwallEnglish
The two blocks on either side of a sloping fault. The hanging wall is the block above the fault surface; the footwall is the block below it.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.1 (grade 6)
The two blocks on either side of a sloping fault. The hanging wall is the block above the fault surface; the footwall is the block below it.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.1 (grade 6)
hardEnglish
Not easy to scratch or dent. A hard rock stays the same when you rub a coin on it.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.2 (grade K)
Not easy to scratch or dent. A hard rock stays the same when you rub a coin on it.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.2 (grade K)
hardnessEnglish
How well a mineral stands up to being scratched.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.1 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.2 (grade 3)
How well a mineral stands up to being scratched.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.1 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.2 (grade 3)
harmonic tremorEnglish
A steady, humming ground vibration that lasts minutes or hours, caused by magma or gas moving through cracks; a strong sign an eruption may be near.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.2 (grade 6)
A steady, humming ground vibration that lasts minutes or hours, caused by magma or gas moving through cracks; a strong sign an eruption may be near.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.2 (grade 6)
hatchEnglish
To break out of an egg.
Grade 2 Life Science: Animal Families, Lesson 8.2 (grade 2) · Kindergarten Life Science: God Made the Animals, Lesson 1.2 (grade K) · Kindergarten Life Science: God Made the Animals, Lesson 3.2 (grade K) · +1 more
To break out of an egg.
Grade 2 Life Science: Animal Families, Lesson 8.2 (grade 2) · Kindergarten Life Science: God Made the Animals, Lesson 1.2 (grade K) · Kindergarten Life Science: God Made the Animals, Lesson 3.2 (grade K) · +1 more
hazard mapEnglish
A map that shows where a danger is likely: the floodplain of a river, the runup zone of a tsunami, slopes that have slid, ash and lahar paths near a volcano.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.4 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 9.3 (grade 6)
A map that shows where a danger is likely: the floodplain of a river, the runup zone of a tsunami, slopes that have slid, ash and lahar paths near a volcano.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.4 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 9.3 (grade 6)
head currentEnglish
A current flowing against the direction a ship is trying to go, which slows the ship down.
Grade 4 Earth Science: Weather and Water, Lesson 7.4 (grade 4)
A current flowing against the direction a ship is trying to go, which slows the ship down.
Grade 4 Earth Science: Weather and Water, Lesson 7.4 (grade 4)
heartEnglish
A strong, hollow muscle about the size of your fist with four chambers. It squeezes to pump blood.
Grade 5 Life Science: The Human Body, Lesson 3.1 (grade 5) · Kindergarten Life Science: God Made the Animals, Lesson 6.1 (grade K) · Grade 1 Physical Education & Health, Lesson 5.1 (grade 1) · +3 more
A strong, hollow muscle about the size of your fist with four chambers. It squeezes to pump blood.
Grade 5 Life Science: The Human Body, Lesson 3.1 (grade 5) · Kindergarten Life Science: God Made the Animals, Lesson 6.1 (grade K) · Grade 1 Physical Education & Health, Lesson 5.1 (grade 1) · +3 more
heart rateEnglish
How many times the heart beats in one minute, written in beats per minute (bpm).
Grade 5 Life Science: The Human Body, Lesson 3.2 (grade 5) · Grade 5 Life Science: The Human Body, Lesson 9.3 (grade 5) · Grade 3 Physical Education & Health, Lesson 5.1 (grade 3) · +2 more
How many times the heart beats in one minute, written in beats per minute (bpm).
Grade 5 Life Science: The Human Body, Lesson 3.2 (grade 5) · Grade 5 Life Science: The Human Body, Lesson 9.3 (grade 5) · Grade 3 Physical Education & Health, Lesson 5.1 (grade 3) · +2 more
hemisphereEnglish
Half of the Earth. The equator divides Earth into the Northern Hemisphere and the Southern Hemisphere.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.1 (grade 5) · Grade 3 Engineering & Physics, Lesson 7.1 (grade 3) · Explore Travel and Faraway Places · Ranger, Stop 1.1 (Ages 10–13) · +3 more
Half of the Earth. The equator divides Earth into the Northern Hemisphere and the Southern Hemisphere.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.1 (grade 5) · Grade 3 Engineering & Physics, Lesson 7.1 (grade 3) · Explore Travel and Faraway Places · Ranger, Stop 1.1 (Ages 10–13) · +3 more
hemophiliaEnglish
An inherited condition in which the blood lacks a working clotting protein, so bleeding takes a long time to stop. Its genes are on the X chromosome.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.4 (grade 8)
An inherited condition in which the blood lacks a working clotting protein, so bleeding takes a long time to stop. Its genes are on the X chromosome.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.4 (grade 8)
hiatusEnglish
A gap in the rock record where time passed but little or no sediment was preserved.
High School Geology, Lesson 6.2 (grade 9–12)
A gap in the rock record where time passed but little or no sediment was preserved.
High School Geology, Lesson 6.2 (grade 9–12)
hibernateEnglish
To sleep very deeply through the winter, the way woodchucks do.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.4 (grade K) · Explore Animals, Stop 1.7 (Ages 7–9) · Explore Animals, Stop 6.3 (Ages 7–9) · +2 more
To sleep very deeply through the winter, the way woodchucks do.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.4 (grade K) · Explore Animals, Stop 1.7 (Ages 7–9) · Explore Animals, Stop 6.3 (Ages 7–9) · +2 more
high tideEnglish
The time when the sea has come far up the beach.
Grade 2 Earth Science: The Earth's Surface, Lesson 6.1 (grade 2)
The time when the sea has come far up the beach.
Grade 2 Earth Science: The Earth's Surface, Lesson 6.1 (grade 2)
high-pressure area (high)English
A large area where air pressure is higher than around it. The air sinks, and the weather is usually fair. Marked H on a map.
Grade 4 Earth Science: Weather and Water, Lesson 2.4 (grade 4)
A large area where air pressure is higher than around it. The air sinks, and the weather is usually fair. Marked H on a map.
Grade 4 Earth Science: Weather and Water, Lesson 2.4 (grade 4)
hillEnglish
A rise of land that is lower and gentler than a mountain.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.3 (grade 2) · Grade 2 Earth Science: The Earth's Surface, Lesson 9.1 (grade 2) · Grade 1 Geography: Maps and Journeys, Lesson 3.1 (grade 1) · +1 more
A rise of land that is lower and gentler than a mountain.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.3 (grade 2) · Grade 2 Earth Science: The Earth's Surface, Lesson 9.1 (grade 2) · Grade 1 Geography: Maps and Journeys, Lesson 3.1 (grade 1) · +1 more
hinge and limbsEnglish
The hinge is the line of sharpest bending in a fold; the limbs are the two sloping sides on either side of it.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.2 (grade 6)
The hinge is the line of sharpest bending in a fold; the limbs are the two sloping sides on either side of it.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.2 (grade 6)
hip bonesEnglish
The strong bones that join the back legs to the backbone. You have them, and so did every dinosaur.
Grade 2 Life Science: Animal Families, Lesson 7.1 (grade 2)
The strong bones that join the back legs to the backbone. You have them, and so did every dinosaur.
Grade 2 Life Science: Animal Families, Lesson 7.1 (grade 2)
hippocampusEnglish
A curved part deep inside each side of the brain, named for its seahorse shape, that helps turn new experiences into long-term memories.
Grade 5 Life Science: The Human Body, Lesson 6.3 (grade 5)
A curved part deep inside each side of the brain, named for its seahorse shape, that helps turn new experiences into long-term memories.
Grade 5 Life Science: The Human Body, Lesson 6.3 (grade 5)
hollow boneEnglish
A bone with an air space inside instead of being solid all the way through.
Grade 2 Life Science: Animal Families, Lesson 2.1 (grade 2)
A bone with an air space inside instead of being solid all the way through.
Grade 2 Life Science: Animal Families, Lesson 2.1 (grade 2)
hollow bonesEnglish
Bones with air spaces inside, which are strong but light. Theropods and birds both have them.
Grade 4 Life Science: Classification, Lesson 7.2 (grade 4)
Bones with air spaces inside, which are strong but light. Theropods and birds both have them.
Grade 4 Life Science: Classification, Lesson 7.2 (grade 4)
hollow tubeEnglish
A shape with its material spread out around an empty middle, like a bicycle frame or a bone. A tube is much stiffer than a solid rod made of the same amount of material.
Grade 6 Life Science: Animal Design and Behavior, Lesson 7.4 (grade 6)
A shape with its material spread out around an empty middle, like a bicycle frame or a bone. A tube is much stiffer than a solid rod made of the same amount of material.
Grade 6 Life Science: Animal Design and Behavior, Lesson 7.4 (grade 6)
honeybeeEnglish
A bee that lives in a big family in a hive and makes honey and wax. It is an insect with six legs and four wings.
Grade 2 Life Science: Animal Families, Lesson 6.3 (grade 2) · Kindergarten Life Science: God Made the Animals, Lesson 4.4 (grade K)
A bee that lives in a big family in a hive and makes honey and wax. It is an insect with six legs and four wings.
Grade 2 Life Science: Animal Families, Lesson 6.3 (grade 2) · Kindergarten Life Science: God Made the Animals, Lesson 4.4 (grade K)
hook echoEnglish
A hook-shaped curl of rain on the radar screen on the back side of a supercell, where rotation wraps rain around a possible tornado.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.2 (grade 8)
A hook-shaped curl of rain on the radar screen on the back side of a supercell, where rotation wraps rain around a possible tornado.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.2 (grade 8)
hook-and-loop fastenerEnglish
A fastener with tiny stiff hooks on one strip and soft loops on the other. Velcro is the brand name of the first one.
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.1 (grade 6)
A fastener with tiny stiff hooks on one strip and soft loops on the other. Velcro is the brand name of the first one.
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.1 (grade 6)
hootEnglish
The deep call an owl makes at night: hoo, hoo-hoo, hoo, hoo.
Grade 1 Life Science: Animal Homes and Habits, Lesson 1.3 (grade 1)
The deep call an owl makes at night: hoo, hoo-hoo, hoo, hoo.
Grade 1 Life Science: Animal Homes and Habits, Lesson 1.3 (grade 1)
hour linesEnglish
The lines marked on a sundial’s face where the shadow falls at each hour.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.2 (grade 5)
The lines marked on a sundial’s face where the shadow falls at each hour.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.2 (grade 5)
humidityEnglish
How much water vapor is in the air. Humid air feels damp and muggy; dry air feels crisp.
Grade 4 Earth Science: Weather and Water, Lesson 1.3 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 8.3 (grade 4) · Grade 6 Engineering & Physics, Lesson 3.4 (grade 6) · +3 more
How much water vapor is in the air. Humid air feels damp and muggy; dry air feels crisp.
Grade 4 Earth Science: Weather and Water, Lesson 1.3 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 8.3 (grade 4) · Grade 6 Engineering & Physics, Lesson 3.4 (grade 6) · +3 more
humpEnglish
The big lump on a camel’s back. It is full of fat, which is food the camel’s body saves for later.
Grade 1 Life Science: Animal Homes and Habits, Lesson 4.1 (grade 1)
The big lump on a camel’s back. It is full of fat, which is food the camel’s body saves for later.
Grade 1 Life Science: Animal Homes and Habits, Lesson 4.1 (grade 1)
humusEnglish
The dark, soft part of soil made from old leaves and plants that have rotted away. It soaks up water like a sponge.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 2.3 (grade 1) · Grade 6 Earth Science: The Dynamic Earth, Lesson 9.2 (grade 6) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.2 (grade 8) · +3 more
The dark, soft part of soil made from old leaves and plants that have rotted away. It soaks up water like a sponge.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 2.3 (grade 1) · Grade 6 Earth Science: The Dynamic Earth, Lesson 9.2 (grade 6) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.2 (grade 8) · +3 more
hunting seasonEnglish
The dates set by law when a game animal may be hunted, chosen to avoid the times when the animals are mating, nesting or raising young.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 7.4 (grade 8)
The dates set by law when a game animal may be hunted, chosen to avoid the times when the animals are mating, nesting or raising young.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 7.4 (grade 8)
hurricaneEnglish
A huge spinning storm that forms over warm ocean water and has steady winds of at least 119 km/h (74 mph).
Grade 4 Earth Science: Weather and Water, Lesson 4.1 (grade 4) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 2.4 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 8.3 (grade 6)
A huge spinning storm that forms over warm ocean water and has steady winds of at least 119 km/h (74 mph).
Grade 4 Earth Science: Weather and Water, Lesson 4.1 (grade 4) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 2.4 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 8.3 (grade 6)
hybridizationEnglish
The mating of two different species or varieties to produce offspring (a hybrid), such as a horse and donkey producing a mule.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.4 (grade 8)
The mating of two different species or varieties to produce offspring (a hybrid), such as a horse and donkey producing a mule.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.4 (grade 8)
hydraulic fracturingEnglish
Cracking shale with water and sand pumped at high pressure so that oil and gas can flow to a horizontal well.
High School Geology, Lesson 7.3 (grade 9–12)
Cracking shale with water and sand pumped at high pressure so that oil and gas can flow to a horizontal well.
High School Geology, Lesson 7.3 (grade 9–12)
hydrocarbonEnglish
A molecule made of hydrogen and carbon atoms. Crude oil and natural gas are mixtures of hydrocarbons of many sizes, from methane (one carbon) to asphalt (dozens of carbons).
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.4 (grade 8)
A molecule made of hydrogen and carbon atoms. Crude oil and natural gas are mixtures of hydrocarbons of many sizes, from methane (one carbon) to asphalt (dozens of carbons).
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.4 (grade 8)
hydroelectric powerEnglish
Electricity made when falling water from a dam spins machines called turbines.
Grade 4 Earth Science: Weather and Water, Lesson 6.2 (grade 4) · Grade 7 Geography: Regions of the World, Lesson 4.4 (grade 7) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 6.4 (grade 8)
Electricity made when falling water from a dam spins machines called turbines.
Grade 4 Earth Science: Weather and Water, Lesson 6.2 (grade 4) · Grade 7 Geography: Regions of the World, Lesson 4.4 (grade 7) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 6.4 (grade 8)
hydrologistEnglish
A scientist who forecasts rivers and floods from rain, snowmelt and soil conditions; the NWS runs 13 river forecast centers.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.4 (grade 8)
A scientist who forecasts rivers and floods from rain, snowmelt and soil conditions; the NWS runs 13 river forecast centers.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.4 (grade 8)
hydrostatic skeletonEnglish
A body support made of fluid held under pressure inside a muscular body wall, as in the earthworm, instead of bones.
Grade 7 Life Science: Cells and Microbes, Lesson 8.4 (grade 7)
A body support made of fluid held under pressure inside a muscular body wall, as in the earthworm, instead of bones.
Grade 7 Life Science: Cells and Microbes, Lesson 8.4 (grade 7)
hypha (plural hyphae)English
One thin, branching thread of a fungus, usually only a few micrometers wide. Hyphae grow at their tips.
Grade 7 Life Science: Cells and Microbes, Lesson 6.1 (grade 7)
One thin, branching thread of a fungus, usually only a few micrometers wide. Hyphae grow at their tips.
Grade 7 Life Science: Cells and Microbes, Lesson 6.1 (grade 7)
I
I wonderEnglish
A question you write about something you saw. Scientists begin with questions.
Grade 2 Life Science: Animal Families, Lesson 9.1 (grade 2)
A question you write about something you saw. Scientists begin with questions.
Grade 2 Life Science: Animal Families, Lesson 9.1 (grade 2)
ice ageEnglish
A museum and textbook word for a time when glaciers covered much more of the earth’s land than they do now.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.1 (grade 7) · Explore Dinosaurs · Expert, Stop 5.6 (Ages 14+) · Explore Dinosaurs · Ranger, Stop 5.6 (Ages 10–13) · +1 more
A museum and textbook word for a time when glaciers covered much more of the earth’s land than they do now.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.1 (grade 7) · Explore Dinosaurs · Expert, Stop 5.6 (Ages 14+) · Explore Dinosaurs · Ranger, Stop 5.6 (Ages 10–13) · +1 more
ice coreEnglish
A long cylinder of ice, about 10 cm across, drilled from an ice sheet in sections and stored frozen so its layers can be studied.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.4 (grade 7)
A long cylinder of ice, about 10 cm across, drilled from an ice sheet in sections and stored frozen so its layers can be studied.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.4 (grade 7)
ice damEnglish
A wall of glacier ice that blocks a river valley and holds back a lake.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.1 (grade 6)
A wall of glacier ice that blocks a river valley and holds back a lake.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.1 (grade 6)
ice giantEnglish
A giant planet, such as Uranus or Neptune, made mostly of water, ammonia and methane ices around a small rocky center, under a thick layer of gas.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.3 (grade 5)
A giant planet, such as Uranus or Neptune, made mostly of water, ammonia and methane ices around a small rocky center, under a thick layer of gas.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.3 (grade 5)
ice sheetEnglish
A glacier so large it covers a whole region, like those on Greenland and Antarctica today.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.3 (grade 7) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 4.4 (grade 3)
A glacier so large it covers a whole region, like those on Greenland and Antarctica today.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.3 (grade 7) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 4.4 (grade 3)
icebergEnglish
A big chunk of glacier ice that broke off and floats in the sea.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.3 (grade 2) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 4.4 (grade 3)
A big chunk of glacier ice that broke off and floats in the sea.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.3 (grade 2) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 4.4 (grade 3)
Iceland sparEnglish
Very clear calcite, first found in Iceland, that makes anything seen through it look double.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.4 (grade 3)
Very clear calcite, first found in Iceland, that makes anything seen through it look double.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.4 (grade 3)
ichthyosaurEnglish
A big sea reptile shaped a bit like a dolphin. Its name means “fish lizard,” but it was not a fish and not a lizard.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.1 (grade 1) · Explore Dinosaurs · Expert, Stop 2.1 (Ages 14+) · Explore Dinosaurs · Expert, Stop 5.1 (Ages 14+) · +3 more
A big sea reptile shaped a bit like a dolphin. Its name means “fish lizard,” but it was not a fish and not a lizard.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.1 (grade 1) · Explore Dinosaurs · Expert, Stop 2.1 (Ages 14+) · Explore Dinosaurs · Expert, Stop 5.1 (Ages 14+) · +3 more
identification keyEnglish
A list of paired choices that leads you, one step at a time, to the name of a mystery specimen.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 8.4 (grade 3)
A list of paired choices that leads you, one step at a time, to the name of a mystery specimen.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 8.4 (grade 3)
identifyEnglish
To find out the name of a living thing by looking carefully at its features.
Grade 4 Life Science: Classification, Lesson 1.4 (grade 4)
To find out the name of a living thing by looking carefully at its features.
Grade 4 Life Science: Classification, Lesson 1.4 (grade 4)
igneous rockEnglish
Rock that forms when melted rock cools and hardens. The name comes from ignis, the Latin word for fire.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.1 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.1 (grade 3)
Rock that forms when melted rock cools and hardens. The name comes from ignis, the Latin word for fire.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.1 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.1 (grade 3)
image of GodEnglish
The special likeness to God given to human beings alone, male and female (Genesis 1:27), which sets people apart from animals and gives every person dignity.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.1 (grade 8)
The special likeness to God given to human beings alone, male and female (Genesis 1:27), which sets people apart from animals and gives every person dignity.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.1 (grade 8)
imbricationEnglish
Flat pebbles stacked by moving water so that they lean upstream, overlapping like roof shingles.
Grade 7 Earth Science: Earth History and the Flood, Lesson 9.3 (grade 7)
Flat pebbles stacked by moving water so that they lean upstream, overlapping like roof shingles.
Grade 7 Earth Science: Earth History and the Flood, Lesson 9.3 (grade 7)
impactEnglish
When one thing crashes into another thing hard and fast.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.4 (grade 1)
When one thing crashes into another thing hard and fast.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.4 (grade 1)
inbreedingEnglish
Breeding closely related animals. It makes it more likely that a puppy inherits two copies of the same harmful recessive allele.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.2 (grade 8)
Breeding closely related animals. It makes it more likely that a puppy inherits two copies of the same harmful recessive allele.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.2 (grade 8)
incisors, canines, premolars, molarsEnglish
The four kinds of teeth: incisors cut, canines tear, premolars crush, and molars grind food.
Grade 5 Life Science: The Human Body, Lesson 5.2 (grade 5)
The four kinds of teeth: incisors cut, canines tear, premolars crush, and molars grind food.
Grade 5 Life Science: The Human Body, Lesson 5.2 (grade 5)
inclination (dip)English
The angle at which a freely hanging compass needle tilts below level: about 0° near the equator and about 90° at the magnetic poles.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.3 (grade 6)
The angle at which a freely hanging compass needle tilts below level: about 0° near the equator and about 90° at the magnetic poles.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.3 (grade 6)
inclusionEnglish
A piece of one rock enclosed inside another; the enclosed piece is older than the rock around it.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.4 (grade 7)
A piece of one rock enclosed inside another; the enclosed piece is older than the rock around it.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.4 (grade 7)
index contourEnglish
A heavier contour line, usually every fifth one, labeled with its elevation so you can find your place in the pattern quickly.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.2 (grade 8) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 1.1 (grade 6)
A heavier contour line, usually every fifth one, labeled with its elevation so you can find your place in the pattern quickly.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.2 (grade 8) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 1.1 (grade 6)
index fossilEnglish
A fossil found in only a narrow set of layers over a wide area, used to match layers from place to place.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.2 (grade 7) · High School Geology, Lesson 5.3 (grade 9–12)
A fossil found in only a narrow set of layers over a wide area, used to match layers from place to place.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.2 (grade 7) · High School Geology, Lesson 5.3 (grade 9–12)
indirect flight musclesEnglish
Flight muscles that do not touch the wings but squeeze and stretch the box of the thorax, which levers the wings up and down. Flies, bees and wasps fly this way.
Grade 6 Life Science: Animal Design and Behavior, Lesson 1.3 (grade 6)
Flight muscles that do not touch the wings but squeeze and stretch the box of the thorax, which levers the wings up and down. Flies, bees and wasps fly this way.
Grade 6 Life Science: Animal Design and Behavior, Lesson 1.3 (grade 6)
inertiaEnglish
The way an object keeps doing what it is doing, staying still or moving in a straight line at the same speed, until a force changes it.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.3 (grade 5) · Grade 6 Earth Science: The Dynamic Earth, Lesson 4.3 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 8.1 (grade 6) · +3 more
The way an object keeps doing what it is doing, staying still or moving in a straight line at the same speed, until a force changes it.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.3 (grade 5) · Grade 6 Earth Science: The Dynamic Earth, Lesson 4.3 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 8.1 (grade 6) · +3 more
infectionEnglish
When harmful germs get into the body and grow, causing redness, swelling, pus, fever or worse.
Grade 5 Life Science: The Human Body, Lesson 8.3 (grade 5)
When harmful germs get into the body and grow, causing redness, swelling, pus, fever or worse.
Grade 5 Life Science: The Human Body, Lesson 8.3 (grade 5)
inference to the best explanationEnglish
Choosing the cause that best accounts for all the evidence, the way a detective reasons from clues to the most likely culprit.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.1 (grade 8)
Choosing the cause that best accounts for all the evidence, the way a detective reasons from clues to the most likely culprit.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.1 (grade 8)
infiltrationEnglish
Water soaking down into the ground from the surface.
Grade 4 Earth Science: Weather and Water, Lesson 1.4 (grade 4) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.3 (grade 8)
Water soaking down into the ground from the surface.
Grade 4 Earth Science: Weather and Water, Lesson 1.4 (grade 4) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.3 (grade 8)
inflammationEnglish
The body’s general response to injury or infection: redness, warmth, swelling and pain as blood and defender cells rush to the spot.
Grade 7 Life Science: Cells and Microbes, Lesson 4.4 (grade 7)
The body’s general response to injury or infection: redness, warmth, swelling and pain as blood and defender cells rush to the spot.
Grade 7 Life Science: Cells and Microbes, Lesson 4.4 (grade 7)
infrared lightEnglish
Light with longer waves than red light. Our eyes cannot see it, but we feel much of it as warmth. It can pass through clouds of dust.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.2 (grade 5)
Light with longer waves than red light. Our eyes cannot see it, but we feel much of it as warmth. It can pass through clouds of dust.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.2 (grade 5)
initial conditionsEnglish
The amounts of parent and daughter present when the rock formed. These must be assumed or argued for, since no one measured them.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.2 (grade 7)
The amounts of parent and daughter present when the rock formed. These must be assumed or argued for, since no one measured them.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.2 (grade 7)
innate behaviorEnglish
Behavior an animal is born ready to do, without being taught. Instincts and reflexes are innate.
Grade 6 Life Science: Animal Design and Behavior, Lesson 5.4 (grade 6)
Behavior an animal is born ready to do, without being taught. Instincts and reflexes are innate.
Grade 6 Life Science: Animal Design and Behavior, Lesson 5.4 (grade 6)
inner barkEnglish
The soft, living layer just under the rough outer bark. It carries food from the leaves down to the roots.
Grade 1 Life Science: Animal Homes and Habits, Lesson 6.4 (grade 1)
The soft, living layer just under the rough outer bark. It carries food from the leaves down to the roots.
Grade 1 Life Science: Animal Homes and Habits, Lesson 6.4 (grade 1)
inner coreEnglish
The solid ball of iron and nickel at Earth’s center, about 1,220 km in radius, discovered by Inge Lehmann in 1936.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.1 (grade 6)
The solid ball of iron and nickel at Earth’s center, about 1,220 km in radius, discovered by Inge Lehmann in 1936.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.1 (grade 6)
intelligent designEnglish
The view that certain features of the universe and of living things are best explained by an intelligent cause, not by an undirected process such as natural selection.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.3 (grade 8)
The view that certain features of the universe and of living things are best explained by an intelligent cause, not by an undirected process such as natural selection.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.3 (grade 8)
interior roomEnglish
A room in the middle of a building with no walls or windows to the outside.
Grade 4 Earth Science: Weather and Water, Lesson 9.3 (grade 4)
A room in the middle of a building with no walls or windows to the outside.
Grade 4 Earth Science: Weather and Water, Lesson 9.3 (grade 4)
interstate compactEnglish
A formal agreement between states, approved by Congress, that divides the water of a river that crosses state lines.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.4 (grade 8)
A formal agreement between states, approved by Congress, that divides the water of a river that crosses state lines.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.4 (grade 8)
interstellar spaceEnglish
The space between the stars, beyond the region where the Sun’s steady outflow of particles, called the solar wind, holds sway.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.4 (grade 5)
The space between the stars, beyond the region where the Sun’s steady outflow of particles, called the solar wind, holds sway.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.4 (grade 5)
intervalEnglish
The time between one event and the next, such as between one clap and the next.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.4 (grade 6) · Grade 3 Physical Education & Health, Lesson 5.2 (grade 3) · Grade 4 Physical Education & Health, Lesson 4.2 (grade 4)
The time between one event and the next, such as between one clap and the next.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.4 (grade 6) · Grade 3 Physical Education & Health, Lesson 5.2 (grade 3) · Grade 4 Physical Education & Health, Lesson 4.2 (grade 4)
intrusiveEnglish
Igneous rock that cooled slowly underground and therefore has large, visible crystals; granite and gabbro are examples.
High School Geology, Lesson 1.2 (grade 9–12)
Igneous rock that cooled slowly underground and therefore has large, visible crystals; granite and gabbro are examples.
High School Geology, Lesson 1.2 (grade 9–12)
invertebrateEnglish
An animal without a backbone, such as a spider, crab, snail, worm or starfish.
Grade 4 Life Science: Classification, Lesson 2.1 (grade 4) · Grade 4 Life Science: Classification, Lesson 3.1 (grade 4)
An animal without a backbone, such as a spider, crab, snail, worm or starfish.
Grade 4 Life Science: Classification, Lesson 2.1 (grade 4) · Grade 4 Life Science: Classification, Lesson 3.1 (grade 4)
irisEnglish
The colored ring around the pupil. It may be brown, blue, green or gray.
Grade 1 Life Science: Animal Homes and Habits, Lesson 8.1 (grade 1) · Grade 5 Life Science: The Human Body, Lesson 7.1 (grade 5)
The colored ring around the pupil. It may be brown, blue, green or gray.
Grade 1 Life Science: Animal Homes and Habits, Lesson 8.1 (grade 1) · Grade 5 Life Science: The Human Body, Lesson 7.1 (grade 5)
iris and pupilEnglish
The iris is the colored ring of muscle in the eye; the pupil is the opening in its center. The iris widens or narrows the pupil to let in more or less light.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.2 (grade 8)
The iris is the colored ring of muscle in the eye; the pupil is the opening in its center. The iris widens or narrows the pupil to let in more or less light.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.2 (grade 8)
irreducible complexityEnglish
Michael Behe’s term for a single system of several well-matched parts that all work together for its basic job, so that removing any one part makes the system stop working.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.3 (grade 8) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.3 (grade 8)
Michael Behe’s term for a single system of several well-matched parts that all work together for its basic job, so that removing any one part makes the system stop working.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.3 (grade 8) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.3 (grade 8)
islandEnglish
Land with water all around it.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.4 (grade 2) · Explore Animals, Stop 3.2 (Ages 7–9) · Grade 1 Geography: Maps and Journeys, Lesson 9.3 (grade 1) · +3 more
Land with water all around it.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.4 (grade 2) · Explore Animals, Stop 3.2 (Ages 7–9) · Grade 1 Geography: Maps and Journeys, Lesson 9.3 (grade 1) · +3 more
isobarEnglish
A line on a weather map that connects places with the same air pressure.
Grade 4 Earth Science: Weather and Water, Lesson 2.4 (grade 4)
A line on a weather map that connects places with the same air pressure.
Grade 4 Earth Science: Weather and Water, Lesson 2.4 (grade 4)
isolation experimentEnglish
An experiment in which an animal is raised without the chance to learn a behavior from others, to test whether the behavior is innate.
Grade 6 Life Science: Animal Design and Behavior, Lesson 5.4 (grade 6)
An experiment in which an animal is raised without the chance to learn a behavior from others, to test whether the behavior is innate.
Grade 6 Life Science: Animal Design and Behavior, Lesson 5.4 (grade 6)
isostasyEnglish
The floating balance of the crust on the denser mantle, by which mountains have deep roots like icebergs and rise as they erode.
High School Geology, Lesson 2.4 (grade 9–12)
The floating balance of the crust on the denser mantle, by which mountains have deep roots like icebergs and rise as they erode.
High School Geology, Lesson 2.4 (grade 9–12)
isotopeEnglish
A form of an element with a particular number of neutrons in its nucleus. Carbon-12 and carbon-14 are both carbon, but carbon-14 has two extra neutrons and is unstable.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.1 (grade 7) · High School Geology, Lesson 5.4 (grade 9–12)
A form of an element with a particular number of neutrons in its nucleus. Carbon-12 and carbon-14 are both carbon, but carbon-14 has two extra neutrons and is unstable.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.1 (grade 7) · High School Geology, Lesson 5.4 (grade 9–12)
J
jaggedEnglish
Sharp and pointy, with rough corners and edges.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.3 (grade 1)
Sharp and pointy, with rough corners and edges.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.3 (grade 1)
jailerEnglish
The man whose job is to guard a prison and the prisoners in it.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.4 (grade 2)
The man whose job is to guard a prison and the prisoners in it.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.4 (grade 2)
jar testEnglish
A settling test: soil is shaken in water, and sand settles first, then silt, then clay, so the layer thicknesses give the percentages.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.1 (grade 8)
A settling test: soil is shaken in water, and sand settles first, then silt, then clay, so the layer thicknesses give the percentages.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.1 (grade 8)
jaw hingeEnglish
A joint where a jaw can bend. A mosasaur’s lower jaw had an extra hinge partway along each side.
Grade 3 Life Science: Plants and Animals Together, Lesson 7.2 (grade 3)
A joint where a jaw can bend. A mosasaur’s lower jaw had an extra hinge partway along each side.
Grade 3 Life Science: Plants and Animals Together, Lesson 7.2 (grade 3)
Julian calendarEnglish
The calendar begun by Julius Caesar in 46 B.C., with a leap day every fourth year, making its average year 365¼ days.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.3 (grade 5)
The calendar begun by Julius Caesar in 46 B.C., with a leap day every fourth year, making its average year 365¼ days.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.3 (grade 5)
JurassicEnglish
A museum word: the name geologists give to a set of rock layers found around the world, named for the Jura Mountains of France and Switzerland. On a sign it comes with a date; the name itself only labels the layers.
Grade 7 Earth Science: Earth History and the Flood, Lesson 8.2 (grade 7) · Explore Dinosaurs, Stop 1.3 (Ages 7–9) · Explore Dinosaurs, Stop 1.4 (Ages 7–9) · +1 more
A museum word: the name geologists give to a set of rock layers found around the world, named for the Jura Mountains of France and Switzerland. On a sign it comes with a date; the name itself only labels the layers.
Grade 7 Earth Science: Earth History and the Flood, Lesson 8.2 (grade 7) · Explore Dinosaurs, Stop 1.3 (Ages 7–9) · Explore Dinosaurs, Stop 1.4 (Ages 7–9) · +1 more
K
karstEnglish
A landscape formed by the dissolving of limestone or similar rock, marked by sinkholes, disappearing streams, large springs, and caves.
High School Geology, Lesson 4.2 (grade 9–12)
A landscape formed by the dissolving of limestone or similar rock, marked by sinkholes, disappearing streams, large springs, and caves.
High School Geology, Lesson 4.2 (grade 9–12)
keeperEnglish
A person whose job is to feed and care for the animals at a zoo or farm.
Kindergarten Life Science: God Made the Animals, Lesson 9.3 (grade K)
A person whose job is to feed and care for the animals at a zoo or farm.
Kindergarten Life Science: God Made the Animals, Lesson 9.3 (grade K)
keratinEnglish
The tough material that makes hair, fingernails, hooves, horns and porcupine quills.
Grade 3 Life Science: Plants and Animals Together, Lesson 6.1 (grade 3) · Fabrics & Sewing II, Lesson 1.2 (grade 6–8) · Textile Science & Clothing Construction, Lesson 2.1 (grade 9–12)
The tough material that makes hair, fingernails, hooves, horns and porcupine quills.
Grade 3 Life Science: Plants and Animals Together, Lesson 6.1 (grade 3) · Fabrics & Sewing II, Lesson 1.2 (grade 6–8) · Textile Science & Clothing Construction, Lesson 2.1 (grade 9–12)
kerogenEnglish
The waxy organic matter in source rock that breaks down into oil and gas when heated.
High School Geology, Lesson 7.3 (grade 9–12)
The waxy organic matter in source rock that breaks down into oil and gas when heated.
High School Geology, Lesson 7.3 (grade 9–12)
kilnEnglish
A very hot oven that bakes clay until it is hard as stone.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 2.2 (grade 1)
A very hot oven that bakes clay until it is hard as stone.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 2.2 (grade 1)
kimberliteEnglish
A kind of volcanic rock that rose up from very deep in the earth in narrow pipes and carried diamonds with it. It is named for the town of Kimberley in South Africa.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.4 (grade 3)
A kind of volcanic rock that rose up from very deep in the earth in narrow pipes and carried diamonds with it. It is named for the town of Kimberley in South Africa.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.4 (grade 3)
kindEnglish
A family of animals that God made to have babies like themselves, “after his kind” (Genesis 1:25).
Grade 2 Earth Science: The Earth's Surface, Lesson 7.4 (grade 2) · Grade 7 Earth Science: Earth History and the Flood, Lesson 5.2 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 6.1 (grade 7) · +3 more
A family of animals that God made to have babies like themselves, “after his kind” (Genesis 1:25).
Grade 2 Earth Science: The Earth's Surface, Lesson 7.4 (grade 2) · Grade 7 Earth Science: Earth History and the Flood, Lesson 5.2 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 6.1 (grade 7) · +3 more
kindnessEnglish
Being gentle and good to a creature, the way God is good to us.
Kindergarten Life Science: God Made the Animals, Lesson 2.4 (grade K)
Being gentle and good to a creature, the way God is good to us.
Kindergarten Life Science: God Made the Animals, Lesson 2.4 (grade K)
kingdomEnglish
The biggest group in Linnaeus’s system. His first book had three: animals, plants and stones.
Grade 4 Life Science: Classification, Lesson 1.1 (grade 4) · Grade 4 Life Science: Classification, Lesson 1.2 (grade 4)
The biggest group in Linnaeus’s system. His first book had three: animals, plants and stones.
Grade 4 Life Science: Classification, Lesson 1.1 (grade 4) · Grade 4 Life Science: Classification, Lesson 1.2 (grade 4)
kingdom of heavenEnglish
God’s rule in the hearts of His people. Jesus said it starts small and grows very big.
Kindergarten Life Science: God Made the Animals, Lesson 5.4 (grade K)
God’s rule in the hearts of His people. Jesus said it starts small and grows very big.
Kindergarten Life Science: God Made the Animals, Lesson 5.4 (grade K)
kittenEnglish
A baby cat. Kittens are born with their eyes shut and drink their mother’s milk.
Kindergarten Life Science: God Made the Animals, Lesson 2.2 (grade K)
A baby cat. Kittens are born with their eyes shut and drink their mother’s milk.
Kindergarten Life Science: God Made the Animals, Lesson 2.2 (grade K)
L
lab practicalEnglish
A test in which you move from station to station and identify real specimens or structures, often with a time limit at each station.
Grade 7 Life Science: Cells and Microbes, Lesson 8.4 (grade 7)
A test in which you move from station to station and identify real specimens or structures, often with a time limit at each station.
Grade 7 Life Science: Cells and Microbes, Lesson 8.4 (grade 7)
laharEnglish
A fast-moving mudflow of volcanic ash, rock and water, often made when an eruption melts snow and ice.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.4 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 8.2 (grade 6) · High School Geology, Lesson 2.3 (grade 9–12)
A fast-moving mudflow of volcanic ash, rock and water, often made when an eruption melts snow and ice.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.4 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 8.2 (grade 6) · High School Geology, Lesson 2.3 (grade 9–12)
lake-effect snowEnglish
Heavy snow that falls when cold air blows across warm open water, picks up moisture and dumps it downwind. The Great Lakes do this every winter.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.3 (grade 7)
Heavy snow that falls when cold air blows across warm open water, picks up moisture and dumps it downwind. The Great Lakes do this every winter.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.3 (grade 7)
lambEnglish
A baby sheep. The mother sheep is a ewe, and the father is a ram.
Kindergarten Life Science: God Made the Animals, Lesson 1.3 (grade K)
A baby sheep. The mother sheep is a ewe, and the father is a ram.
Kindergarten Life Science: God Made the Animals, Lesson 1.3 (grade K)
lamina (plural laminae)English
A very thin layer of sediment, less than 1 cm thick; a stack of laminae makes up a bed.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.3 (grade 7)
A very thin layer of sediment, less than 1 cm thick; a stack of laminae makes up a bed.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.3 (grade 7)
landformEnglish
A shape of the land, like a hill, a valley or a flat plain.
Grade 2 Earth Science: The Earth's Surface, Lesson 9.1 (grade 2) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 5.1 (grade 4) · Kindergarten Geography: God Made the Earth: My First Maps, Lesson 3.1 (grade K)
A shape of the land, like a hill, a valley or a flat plain.
Grade 2 Earth Science: The Earth's Surface, Lesson 9.1 (grade 2) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 5.1 (grade 4) · Kindergarten Geography: God Made the Earth: My First Maps, Lesson 3.1 (grade K)
lapidaryEnglish
A craftsman who cuts and polishes gemstones, or the craft itself.
High School Geology, Lesson 7.2 (grade 9–12)
A craftsman who cuts and polishes gemstones, or the craft itself.
High School Geology, Lesson 7.2 (grade 9–12)
lapse rateEnglish
How fast the air cools with height, in degrees Celsius per kilometer. In the lower atmosphere it averages about 6.5 °C per km.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.1 (grade 8) · Explore Travel and Faraway Places · Expert, Stop 4.5 (Ages 14+) · Geography and History: Why Borders Fall Where They Do, Lesson 3.2 (grade 9–12)
How fast the air cools with height, in degrees Celsius per kilometer. In the lower atmosphere it averages about 6.5 °C per km.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.1 (grade 8) · Explore Travel and Faraway Places · Expert, Stop 4.5 (Ages 14+) · Geography and History: Why Borders Fall Where They Do, Lesson 3.2 (grade 9–12)
large intestineEnglish
The wider tube, about 1.5 meters (5 feet) long, that takes water back into the body and forms the leftover waste.
Grade 5 Life Science: The Human Body, Lesson 5.3 (grade 5)
The wider tube, about 1.5 meters (5 feet) long, that takes water back into the body and forms the leftover waste.
Grade 5 Life Science: The Human Body, Lesson 5.3 (grade 5)
lateral continuityEnglish
Steno’s rule that a layer of sediment spreads out in all directions until it thins to nothing or meets a barrier; so layers now separated by a valley were once connected.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.3 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 9.2 (grade 7)
Steno’s rule that a layer of sediment spreads out in all directions until it thins to nothing or meets a barrier; so layers now separated by a valley were once connected.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.3 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 9.2 (grade 7)
latitudeEnglish
How far north or south of the equator a place is, measured in degrees. The equator is 0°, and the North and South Poles are 90°.
Grade 4 Earth Science: Weather and Water, Lesson 8.1 (grade 4) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.1 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.1 (grade 5) · +3 more
How far north or south of the equator a place is, measured in degrees. The equator is 0°, and the North and South Poles are 90°.
Grade 4 Earth Science: Weather and Water, Lesson 8.1 (grade 4) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.1 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.1 (grade 5) · +3 more
lavaEnglish
Melted rock that has come out on top of the ground. When it cools, it turns hard as rock.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.2 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.1 (grade 3) · Grade 2 Geography: Our Country, Coast to Coast, Lesson 5.4 (grade 2)
Melted rock that has come out on top of the ground. When it cools, it turns hard as rock.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.2 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.1 (grade 3) · Grade 2 Geography: Our Country, Coast to Coast, Lesson 5.4 (grade 2)
law of natureEnglish
A rule that describes how some part of creation always behaves, such as Kepler’s laws for how planets move.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.1 (grade 5)
A rule that describes how some part of creation always behaves, such as Kepler’s laws for how planets move.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.1 (grade 5)
Lazarus taxonEnglish
A kind of creature that disappears from the fossil layers and then turns up again higher, or alive today, as if raised from the dead.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.3 (grade 7)
A kind of creature that disappears from the fossil layers and then turns up again higher, or alive today, as if raised from the dead.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.3 (grade 7)
leader lineEnglish
A straight line drawn from a label to the exact part it names. Leader lines should not cross each other.
Grade 3 Life Science: Plants and Animals Together, Lesson 8.2 (grade 3)
A straight line drawn from a label to the exact part it names. Leader lines should not cross each other.
Grade 3 Life Science: Plants and Animals Together, Lesson 8.2 (grade 3)
leaf stalkEnglish
The narrow part that joins a leaf to the stem. The celery “stalk” we eat is really a big, thick leaf stalk.
Grade 3 Life Science: Plants and Animals Together, Lesson 1.2 (grade 3)
The narrow part that joins a leaf to the stem. The celery “stalk” we eat is really a big, thick leaf stalk.
Grade 3 Life Science: Plants and Animals Together, Lesson 1.2 (grade 3)
leap yearEnglish
A year with an extra day, February 29, added about every four years to make up the extra quarter day in each revolution.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.3 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.3 (grade 5)
A year with an extra day, February 29, added about every four years to make up the extra quarter day in each revolution.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.3 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.3 (grade 5)
learned behaviorEnglish
A behavior an animal gains by experience, practice or being taught, such as a dog learning to sit or a crow learning where food is kept.
Grade 6 Life Science: Animal Design and Behavior, Lesson 5.1 (grade 6) · Grade 6 Life Science: Animal Design and Behavior, Lesson 5.4 (grade 6)
A behavior an animal gains by experience, practice or being taught, such as a dog learning to sit or a crow learning where food is kept.
Grade 6 Life Science: Animal Design and Behavior, Lesson 5.1 (grade 6) · Grade 6 Life Science: Animal Design and Behavior, Lesson 5.4 (grade 6)
leeward sideEnglish
The side of a mountain facing away from the wind, where air comes down. It is usually drier.
Grade 4 Earth Science: Weather and Water, Lesson 8.2 (grade 4)
The side of a mountain facing away from the wind, where air comes down. It is usually drier.
Grade 4 Earth Science: Weather and Water, Lesson 8.2 (grade 4)
left ventricleEnglish
The strongest chamber of the heart, which pumps blood out to the whole body. In a giraffe its wall is especially thick.
Grade 7 Life Science: Cells and Microbes, Lesson 7.4 (grade 7) · Grade 8 Physical Education & Health, Lesson 5.1 (grade 8)
The strongest chamber of the heart, which pumps blood out to the whole body. In a giraffe its wall is especially thick.
Grade 7 Life Science: Cells and Microbes, Lesson 7.4 (grade 7) · Grade 8 Physical Education & Health, Lesson 5.1 (grade 8)
legend (explanation)English
The key to a geologic map: a column of colored boxes, youngest at the top and oldest at the bottom, describing each unit, plus the meaning of every line and symbol.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.4 (grade 8)
The key to a geologic map: a column of colored boxes, youngest at the top and oldest at the bottom, describing each unit, plus the meaning of every line and symbol.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.4 (grade 8)
leveeEnglish
A long wall or bank of earth built along a river to keep flood water in the river channel.
Grade 4 Earth Science: Weather and Water, Lesson 6.2 (grade 4) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 2.4 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 8.2 (grade 6) · +2 more
A long wall or bank of earth built along a river to keep flood water in the river channel.
Grade 4 Earth Science: Weather and Water, Lesson 6.2 (grade 4) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 2.4 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 8.2 (grade 6) · +2 more
levels of organizationEnglish
The order in which a body is built: cells form tissues, tissues form organs, organs form organ systems and organ systems form an organism.
Grade 7 Life Science: Cells and Microbes, Lesson 8.4 (grade 7)
The order in which a body is built: cells form tissues, tissues form organs, organs form organ systems and organ systems form an organism.
Grade 7 Life Science: Cells and Microbes, Lesson 8.4 (grade 7)
lever ruleEnglish
A seesaw balances when mass × distance on one side equals mass × distance on the other side of the pivot.
Grade 6 Life Science: Animal Design and Behavior, Lesson 7.4 (grade 6)
A seesaw balances when mass × distance on one side equals mass × distance on the other side of the pivot.
Grade 6 Life Science: Animal Design and Behavior, Lesson 7.4 (grade 6)
lichenEnglish
A tough, crusty plant-like living thing that grows on rocks and ground. Caribou love to eat it.
Grade 1 Life Science: Animal Homes and Habits, Lesson 5.3 (grade 1) · Grade 6 Life Science: Animal Design and Behavior, Lesson 4.2 (grade 6)
A tough, crusty plant-like living thing that grows on rocks and ground. Caribou love to eat it.
Grade 1 Life Science: Animal Homes and Habits, Lesson 5.3 (grade 1) · Grade 6 Life Science: Animal Design and Behavior, Lesson 4.2 (grade 6)
light pollutionEnglish
Extra light from streetlights, buildings and signs that brightens the night sky and hides fainter stars.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.1 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.3 (grade 5)
Extra light from streetlights, buildings and signs that brightens the night sky and hides fainter stars.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.1 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.3 (grade 5)
light-minuteEnglish
How far light travels in one minute, about 18 million kilometers. The Sun is about 8 light-minutes away.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.4 (grade 5)
How far light travels in one minute, about 18 million kilometers. The Sun is about 8 light-minutes away.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.4 (grade 5)
lightningEnglish
A giant spark of electricity that flashes in a storm, from cloud to cloud or from a cloud to the ground.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.4 (grade K)
A giant spark of electricity that flashes in a storm, from cloud to cloud or from a cloud to the ground.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.4 (grade K)
lightning rodEnglish
A metal rod on top of a building, joined by a wire to the ground, that gives lightning a safe path into the earth.
Grade 4 Earth Science: Weather and Water, Lesson 4.4 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 9.3 (grade 4) · Grade 1 Engineering & Physics, Lesson 4.4 (grade 1)
A metal rod on top of a building, joined by a wire to the ground, that gives lightning a safe path into the earth.
Grade 4 Earth Science: Weather and Water, Lesson 4.4 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 9.3 (grade 4) · Grade 1 Engineering & Physics, Lesson 4.4 (grade 1)
light-yearEnglish
A unit of distance: how far light travels in one year, about 9.5 trillion kilometers (about 5.9 trillion miles). It is not a measure of time.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.4 (grade 5)
A unit of distance: how far light travels in one year, about 9.5 trillion kilometers (about 5.9 trillion miles). It is not a measure of time.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.4 (grade 5)
limeEnglish
Ground limestone (calcium carbonate) spread on soil to raise its pH and supply calcium. Sulfur does the opposite, lowering pH.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.4 (grade 8) · Grade 4 Gardening & Animals, Lesson 3.2 (grade 4) · Grade 6 Gardening & Animals, Lesson 3.1 (grade 6)
Ground limestone (calcium carbonate) spread on soil to raise its pH and supply calcium. Sulfur does the opposite, lowering pH.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.4 (grade 8) · Grade 4 Gardening & Animals, Lesson 3.2 (grade 4) · Grade 6 Gardening & Animals, Lesson 3.1 (grade 6)
limestoneEnglish
A rock that often has sea shells in it. Many buildings and gravel paths are made of it.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.3 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 4.1 (grade 2) · Grade 2 Earth Science: The Earth's Surface, Lesson 7.2 (grade 2) · +3 more
A rock that often has sea shells in it. Many buildings and gravel paths are made of it.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.3 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 4.1 (grade 2) · Grade 2 Earth Science: The Earth's Surface, Lesson 7.2 (grade 2) · +3 more
lindwurmEnglish
The German word for a wingless or two-legged dragon in Central European legends, such as the one on the Klagenfurt fountain.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.3 (grade 7)
The German word for a wingless or two-legged dragon in Central European legends, such as the one on the Klagenfurt fountain.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.3 (grade 7)
literEnglish
A metric unit of volume equal to 1,000 milliliters (mL), a little more than one U.S. quart.
Grade 5 Life Science: The Human Body, Lesson 4.2 (grade 5)
A metric unit of volume equal to 1,000 milliliters (mL), a little more than one U.S. quart.
Grade 5 Life Science: The Human Body, Lesson 4.2 (grade 5)
lithificationEnglish
The process by which loose sediment becomes solid rock through compaction and cementation.
High School Geology, Lesson 1.3 (grade 9–12)
The process by which loose sediment becomes solid rock through compaction and cementation.
High School Geology, Lesson 1.3 (grade 9–12)
lithosphereEnglish
The cold, rigid outer shell of the earth, made of the crust plus the top of the mantle, about 100 km thick and broken into plates.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.2 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 2.3 (grade 6) · High School Geology, Lesson 2.1 (grade 9–12)
The cold, rigid outer shell of the earth, made of the crust plus the top of the mantle, about 100 km thick and broken into plates.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.2 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 2.3 (grade 6) · High School Geology, Lesson 2.1 (grade 9–12)
litterEnglish
Trash left on the ground where it does not belong, like a wrapper in the grass or a can by the road.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 8.2 (grade K) · Grade 1 Gardening & Animals, Lesson 6.3 (grade 1)
Trash left on the ground where it does not belong, like a wrapper in the grass or a can by the road.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 8.2 (grade K) · Grade 1 Gardening & Animals, Lesson 6.3 (grade 1)
living fossilEnglish
Darwin’s phrase for a living creature that closely matches its fossils and has few close living relatives: the coelacanth, the horseshoe crab, the ginkgo.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.3 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.4 (grade 8)
Darwin’s phrase for a living creature that closely matches its fossils and has few close living relatives: the coelacanth, the horseshoe crab, the ginkgo.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.3 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.4 (grade 8)
lizard-hippedEnglish
A dinosaur whose front hip bone, the pubis, points forward toward the head, like a lizard’s.
Grade 2 Life Science: Animal Families, Lesson 7.1 (grade 2)
A dinosaur whose front hip bone, the pubis, points forward toward the head, like a lizard’s.
Grade 2 Life Science: Animal Families, Lesson 7.1 (grade 2)
loaded wordEnglish
A word that signals the writer’s opinion instead of describing, such as “merely,” “so-called,” “obviously” or “blindly”; a fair summary removes them.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.4 (grade 8) · Geopolitics: The Great Ideas, Lesson 5.4 (grade 9–12) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.4 (grade 8)
A word that signals the writer’s opinion instead of describing, such as “merely,” “so-called,” “obviously” or “blindly”; a fair summary removes them.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.4 (grade 8) · Geopolitics: The Great Ideas, Lesson 5.4 (grade 9–12) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.4 (grade 8)
lobeEnglish
A rounded or pointed part that sticks out from the edge of a leaf, like the fingers of a maple leaf or the bumps of an oak leaf.
Grade 3 Life Science: Plants and Animals Together, Lesson 1.3 (grade 3)
A rounded or pointed part that sticks out from the edge of a leaf, like the fingers of a maple leaf or the bumps of an oak leaf.
Grade 3 Life Science: Plants and Animals Together, Lesson 1.3 (grade 3)
lobe finEnglish
A fin carried on a muscular, bony stalk instead of spreading straight from the body. Coelacanths and lungfish have them.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.3 (grade 7)
A fin carried on a muscular, bony stalk instead of spreading straight from the body. Coelacanths and lungfish have them.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.3 (grade 7)
localEnglish
Living or found near your home: your yard, street, park or nearby woods.
Grade 4 Life Science: Classification, Lesson 8.1 (grade 4)
Living or found near your home: your yard, street, park or nearby woods.
Grade 4 Life Science: Classification, Lesson 8.1 (grade 4)
local sun timeEnglish
Time set by the sun in one exact place, so that 12:00 is that place’s solar noon.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.4 (grade 5)
Time set by the sun in one exact place, so that 12:00 is that place’s solar noon.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.4 (grade 5)
localityEnglish
The exact place where a specimen was found.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 8.1 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.4 (grade 3) · Grade 4 Life Science: Classification, Lesson 8.2 (grade 4)
The exact place where a specimen was found.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 8.1 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.4 (grade 3) · Grade 4 Life Science: Classification, Lesson 8.2 (grade 4)
lode depositEnglish
Gold or another metal still locked in the rock where it formed, usually in quartz veins. California’s Mother Lode is a belt of such veins in the Sierra Nevada foothills.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.1 (grade 8)
Gold or another metal still locked in the rock where it formed, usually in quartz veins. California’s Mother Lode is a belt of such veins in the Sierra Nevada foothills.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.1 (grade 8)
loessEnglish
Fine wind-blown silt that piles up in thick blankets; many mammoth remains in Siberia and Alaska are buried in frozen loess.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.2 (grade 7) · Grade 7 Gardening & Animals, Lesson 3.1 (grade 7) · Grade 7 Geography: Regions of the World, Lesson 1.1 (grade 7) · +3 more
Fine wind-blown silt that piles up in thick blankets; many mammoth remains in Siberia and Alaska are buried in frozen loess.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.2 (grade 7) · Grade 7 Gardening & Animals, Lesson 3.1 (grade 7) · Grade 7 Geography: Regions of the World, Lesson 1.1 (grade 7) · +3 more
logbookEnglish
A daily record kept on a ship that tells where the ship was, which way the wind blew, the weather and how the water moved the ship.
Grade 4 Earth Science: Weather and Water, Lesson 7.1 (grade 4) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 8.4 (grade 3)
A daily record kept on a ship that tells where the ship was, which way the wind blew, the weather and how the water moved the ship.
Grade 4 Earth Science: Weather and Water, Lesson 7.1 (grade 4) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 8.4 (grade 3)
longshore driftEnglish
The movement of sand along a shore, caused by waves that strike the beach at an angle.
High School Geology, Lesson 3.4 (grade 9–12)
The movement of sand along a shore, caused by waves that strike the beach at an angle.
High School Geology, Lesson 3.4 (grade 9–12)
long-term memoryEnglish
Memory that can last for days, years or a lifetime, such as your address, a Bible verse you know by heart or how to ride a bike.
Grade 5 Life Science: The Human Body, Lesson 6.3 (grade 5)
Memory that can last for days, years or a lifetime, such as your address, a Bible verse you know by heart or how to ride a bike.
Grade 5 Life Science: The Human Body, Lesson 6.3 (grade 5)
look-alikeEnglish
A different species that is easy to mix up with the one on your page.
Grade 4 Life Science: Classification, Lesson 8.3 (grade 4) · Grade 7 Life Science: Cells and Microbes, Lesson 6.4 (grade 7)
A different species that is easy to mix up with the one on your page.
Grade 4 Life Science: Classification, Lesson 8.3 (grade 4) · Grade 7 Life Science: Cells and Microbes, Lesson 6.4 (grade 7)
loose groundEnglish
Soft ground, like sand or piled-up dirt, that can slide and sink when it is shaken.
Grade 2 Earth Science: The Earth's Surface, Lesson 9.3 (grade 2)
Soft ground, like sand or piled-up dirt, that can slide and sink when it is shaken.
Grade 2 Earth Science: The Earth's Surface, Lesson 9.3 (grade 2)
low tideEnglish
The time when the sea has gone far out and you can see wet sand and rocks.
Grade 2 Earth Science: The Earth's Surface, Lesson 6.1 (grade 2)
The time when the sea has gone far out and you can see wet sand and rocks.
Grade 2 Earth Science: The Earth's Surface, Lesson 6.1 (grade 2)
low-pressure area (low)English
A large area where air pressure is lower than around it. The air rises, and clouds and rain often form. Marked L on a map.
Grade 4 Earth Science: Weather and Water, Lesson 2.4 (grade 4)
A large area where air pressure is lower than around it. The air rises, and clouds and rain often form. Marked L on a map.
Grade 4 Earth Science: Weather and Water, Lesson 2.4 (grade 4)
lowringEnglish
An old English word (also spelled lowering) for a sky that is dark, heavy and threatening.
Grade 4 Earth Science: Weather and Water, Lesson 5.1 (grade 4)
An old English word (also spelled lowering) for a sky that is dark, heavy and threatening.
Grade 4 Earth Science: Weather and Water, Lesson 5.1 (grade 4)
lunar eclipseEnglish
When Earth passes between the Sun and the Moon and Earth’s shadow falls on the Moon. It can happen only at full moon.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.3 (grade 5)
When Earth passes between the Sun and the Moon and Earth’s shadow falls on the Moon. It can happen only at full moon.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.3 (grade 5)
lunar moduleEnglish
The small spaceship that carried two astronauts down to the moon and back up again. Apollo 11’s was named Eagle. Lunar means “of the moon.”
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.3 (grade 1)
The small spaceship that carried two astronauts down to the moon and back up again. Apollo 11’s was named Eagle. Lunar means “of the moon.”
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.3 (grade 1)
lunar monthEnglish
The time from one new moon to the next, about 29½ days.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.2 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.4 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.3 (grade 5)
The time from one new moon to the next, about 29½ days.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.2 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.4 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.3 (grade 5)
lunge feedingEnglish
The way a blue whale eats: it speeds forward, opens its mouth wide, swallows a huge gulp of water and krill, then pushes the water out through its baleen and swallows the krill.
Grade 6 Life Science: Animal Design and Behavior, Lesson 7.1 (grade 6)
The way a blue whale eats: it speeds forward, opens its mouth wide, swallows a huge gulp of water and krill, then pushes the water out through its baleen and swallows the krill.
Grade 6 Life Science: Animal Design and Behavior, Lesson 7.1 (grade 6)
lungsEnglish
The parts inside your chest that fill with air when you breathe. Whales have lungs, just like you.
Grade 2 Life Science: Animal Families, Lesson 1.3 (grade 2) · Grade 2 Life Science: Animal Families, Lesson 4.1 (grade 2) · Grade 5 Life Science: The Human Body, Lesson 4.1 (grade 5) · +3 more
The parts inside your chest that fill with air when you breathe. Whales have lungs, just like you.
Grade 2 Life Science: Animal Families, Lesson 1.3 (grade 2) · Grade 2 Life Science: Animal Families, Lesson 4.1 (grade 2) · Grade 5 Life Science: The Human Body, Lesson 4.1 (grade 5) · +3 more
lunisolar calendarEnglish
A calendar whose months follow the Moon but which adds an extra month in some years so that it stays in step with the Sun and the seasons. The Hebrew calendar is lunisolar.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.4 (grade 5)
A calendar whose months follow the Moon but which adds an extra month in some years so that it stays in step with the Sun and the seasons. The Hebrew calendar is lunisolar.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.4 (grade 5)
lusterEnglish
The way a mineral’s surface shines in the light: metallic (like metal) or nonmetallic (glassy, pearly, silky, greasy or dull).
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.2 (grade 3) · Textile Science & Clothing Construction, Lesson 1.3 (grade 9–12)
The way a mineral’s surface shines in the light: metallic (like metal) or nonmetallic (glassy, pearly, silky, greasy or dull).
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.2 (grade 3) · Textile Science & Clothing Construction, Lesson 1.3 (grade 9–12)
M
made landEnglish
Ground built by filling a marsh, pond or bay edge with loose dirt and rubble. It shakes far more in an earthquake than solid rock.
Grade 6 Earth Science: The Dynamic Earth, Lesson 9.3 (grade 6)
Ground built by filling a marsh, pond or bay edge with loose dirt and rubble. It shakes far more in an earthquake than solid rock.
Grade 6 Earth Science: The Dynamic Earth, Lesson 9.3 (grade 6)
MagiEnglish
The “wise men from the east” in Matthew 2: learned men, probably from Persia or Babylon, who studied the stars and old writings.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.4 (grade 5)
The “wise men from the east” in Matthew 2: learned men, probably from Persia or Babylon, who studied the stars and old writings.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.4 (grade 5)
magmaEnglish
Hot, melted rock that is still deep under the ground.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.2 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.1 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.4 (grade 3) · +1 more
Hot, melted rock that is still deep under the ground.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.2 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.1 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.4 (grade 3) · +1 more
magma and lavaEnglish
Magma is molten rock under the ground; once it flows out onto the surface it is called lava.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.3 (grade 6)
Magma is molten rock under the ground; once it flows out onto the surface it is called lava.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.3 (grade 6)
magma chamberEnglish
A pocket of molten rock and gas under a volcano that feeds its eruptions.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.2 (grade 6)
A pocket of molten rock and gas under a volcano that feeds its eruptions.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.2 (grade 6)
magnetEnglish
An object that attracts iron, nickel and cobalt and has two poles: a north-seeking pole and a south-seeking pole.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.3 (grade 6) · Grade 1 Engineering & Physics, Lesson 4.3 (grade 1) · Grade 3 Engineering & Physics, Lesson 4.3 (grade 3) · +3 more
An object that attracts iron, nickel and cobalt and has two poles: a north-seeking pole and a south-seeking pole.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.3 (grade 6) · Grade 1 Engineering & Physics, Lesson 4.3 (grade 1) · Grade 3 Engineering & Physics, Lesson 4.3 (grade 3) · +3 more
magnetic fieldEnglish
The invisible region of magnetic force around a magnet, which can be mapped with iron filings or a small compass.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.3 (grade 6) · Grade 4 Engineering & Physics, Lesson 4.2 (grade 4) · Grade 5 Engineering & Physics, Lesson 4.2 (grade 5) · +3 more
The invisible region of magnetic force around a magnet, which can be mapped with iron filings or a small compass.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.3 (grade 6) · Grade 4 Engineering & Physics, Lesson 4.2 (grade 4) · Grade 5 Engineering & Physics, Lesson 4.2 (grade 5) · +3 more
magnetic poleEnglish
A place where a magnet’s force is strongest. On Earth, the magnetic poles are the places where a dip needle points straight down or straight up.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.3 (grade 6)
A place where a magnet’s force is strongest. On Earth, the magnetic poles are the places where a dip needle points straight down or straight up.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.3 (grade 6)
magnetic reversalEnglish
A change in which Earth’s magnetic north and south swap places, so a compass would point the opposite way.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.4 (grade 6)
A change in which Earth’s magnetic north and south swap places, so a compass would point the opposite way.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.4 (grade 6)
magnificationEnglish
How many times bigger a telescope or magnifying glass makes something look.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.3 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.1 (grade 5) · Grade 5 Life Science: The Human Body, Lesson 1.1 (grade 5) · +1 more
How many times bigger a telescope or magnifying glass makes something look.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.3 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.1 (grade 5) · Grade 5 Life Science: The Human Body, Lesson 1.1 (grade 5) · +1 more
magnifierEnglish
A curved glass that makes small things look bigger. It is also called a magnifying glass.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 2.1 (grade 1)
A curved glass that makes small things look bigger. It is also called a magnifying glass.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 2.1 (grade 1)
magnifyEnglish
To make something look bigger than it looks to the eye alone. A telescope that magnifies 20 times makes the Moon look 20 times wider.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.1 (grade 5)
To make something look bigger than it looks to the eye alone. A telescope that magnifies 20 times makes the Moon look 20 times wider.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.1 (grade 5)
magnifying glassEnglish
A curved glass that makes small things look bigger when you look through it.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.1 (grade K) · Grade 1 Life Science: Animal Homes and Habits, Lesson 2.4 (grade 1)
A curved glass that makes small things look bigger when you look through it.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.1 (grade K) · Grade 1 Life Science: Animal Homes and Habits, Lesson 2.4 (grade 1)
male and femaleEnglish
A father animal and a mother animal. Every pair on the ark had one of each so there could be babies after the Flood.
Kindergarten Life Science: God Made the Animals, Lesson 8.1 (grade K)
A father animal and a mother animal. Every pair on the ark had one of each so there could be babies after the Flood.
Kindergarten Life Science: God Made the Animals, Lesson 8.1 (grade K)
mammalEnglish
An animal with hair or fur that feeds its babies milk. Dogs, cows, people and bats are mammals.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.3 (grade 2) · Explore Animals · Ranger, Stop 1.3 (Ages 10–13) · Explore Animals, Stop 1.1 (Ages 7–9) · +3 more
An animal with hair or fur that feeds its babies milk. Dogs, cows, people and bats are mammals.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.3 (grade 2) · Explore Animals · Ranger, Stop 1.3 (Ages 10–13) · Explore Animals, Stop 1.1 (Ages 7–9) · +3 more
mandibleEnglish
The lower jaw. In a mouse or vole it comes apart into a left and a right half, so two halves come from one animal.
Grade 7 Life Science: Cells and Microbes, Lesson 8.3 (grade 7)
The lower jaw. In a mouse or vole it comes apart into a left and a right half, so two halves come from one animal.
Grade 7 Life Science: Cells and Microbes, Lesson 8.3 (grade 7)
mantleEnglish
The thick layer of hot, solid rock between the crust and the core, reaching down to about 2,900 km. It can flow very slowly.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.2 (grade 6) · Explore Animals · Expert, Stop 4.4 (Ages 14+) · Explore Animals · Ranger, Stop 4.4 (Ages 10–13) · +2 more
The thick layer of hot, solid rock between the crust and the core, reaching down to about 2,900 km. It can flow very slowly.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.2 (grade 6) · Explore Animals · Expert, Stop 4.4 (Ages 14+) · Explore Animals · Ranger, Stop 4.4 (Ages 10–13) · +2 more
mapEnglish
A drawing of a place as if you were looking down on it from the sky.
Grade 2 Earth Science: The Earth's Surface, Lesson 8.1 (grade 2) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.2 (grade K) · Explore Travel and Faraway Places, Stop 1.1 (Ages 7–9) · +3 more
A drawing of a place as if you were looking down on it from the sky.
Grade 2 Earth Science: The Earth's Surface, Lesson 8.1 (grade 2) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.2 (grade K) · Explore Travel and Faraway Places, Stop 1.1 (Ages 7–9) · +3 more
map scaleEnglish
The rule linking distances on a map to distances on the ground, such as 1 centimeter on the map = 100 meters on the ground.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.4 (grade 5) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.2 (grade 8) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.1 (grade 8) · +3 more
The rule linking distances on a map to distances on the ground, such as 1 centimeter on the map = 100 meters on the ground.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.4 (grade 5) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.2 (grade 8) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.1 (grade 8) · +3 more
map senseEnglish
The ability to know where you are compared to your goal, so you can correct your course if you are moved or blown off course.
Grade 6 Life Science: Animal Design and Behavior, Lesson 2.3 (grade 6)
The ability to know where you are compared to your goal, so you can correct your course if you are moved or blown off course.
Grade 6 Life Science: Animal Design and Behavior, Lesson 2.3 (grade 6)
map unitEnglish
A body of rock or sediment shown as one color on a geologic map, usually a named formation, labeled with a short symbol such as Qal or Ks.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.4 (grade 8) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.1 (grade 8) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.3 (grade 8)
A body of rock or sediment shown as one color on a geologic map, usually a named formation, labeled with a short symbol such as Qal or Ks.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.4 (grade 8) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.1 (grade 8) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.3 (grade 8)
mariaEnglish
The large, dark, smooth plains on the Moon (one is a mare). The word is Latin for “seas,” but they are plains of dark rock with no water.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.1 (grade 5)
The large, dark, smooth plains on the Moon (one is a mare). The word is Latin for “seas,” but they are plains of dark rock with no water.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.1 (grade 5)
marine fossilEnglish
A fossil of something that lived in the sea, such as a clam, a coral, a sea lily or a shark.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.4 (grade 6)
A fossil of something that lived in the sea, such as a clam, a coral, a sea lily or a shark.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.4 (grade 6)
marker layerEnglish
A layer from a known event, such as ash and acid from the Laki eruption of 1783, used to check a layer count.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.4 (grade 7)
A layer from a known event, such as ash and acid from the Laki eruption of 1783, used to check a layer count.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.4 (grade 7)
mark-release-recaptureEnglish
A field method in which animals are marked, set free and later caught again; the share caught again estimates how many survived.
Grade 6 Life Science: Animal Design and Behavior, Lesson 4.2 (grade 6)
A field method in which animals are marked, set free and later caught again; the share caught again estimates how many survived.
Grade 6 Life Science: Animal Design and Behavior, Lesson 4.2 (grade 6)
mass wastingEnglish
Any downhill movement of rock, soil or mud under gravity, from a sudden rockfall to creep too slow to see.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.3 (grade 6)
Any downhill movement of rock, soil or mud under gravity, from a sudden rockfall to creep too slow to see.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.3 (grade 6)
mateEnglish
A bird’s partner. A father bird and a mother bird raise their chicks together.
Kindergarten Life Science: God Made the Animals, Lesson 3.3 (grade K)
A bird’s partner. A father bird and a mother bird raise their chicks together.
Kindergarten Life Science: God Made the Animals, Lesson 3.3 (grade K)
mating flightEnglish
The flight in which winged young queens and males leave the nest to mate. Afterward each new queen sheds her wings and tries to start a colony.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.4 (grade 6)
The flight in which winged young queens and males leave the nest to mate. Afterward each new queen sheds her wings and tries to start a colony.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.4 (grade 6)
mean absolute errorEnglish
The average size of the forecast errors, ignoring whether each was too high or too low. A smaller value means a better forecast.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.4 (grade 8)
The average size of the forecast errors, ignoring whether each was too high or too low. A smaller value means a better forecast.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.4 (grade 8)
meat eaterEnglish
An animal that eats other animals. Scientists call it a carnivore.
Grade 2 Earth Science: The Earth's Surface, Lesson 7.3 (grade 2)
An animal that eats other animals. Scientists call it a carnivore.
Grade 2 Earth Science: The Earth's Surface, Lesson 7.3 (grade 2)
meat-eaterEnglish
An animal that eats other animals. Lions, sharks and Tyrannosaurus rex are meat-eaters.
Kindergarten Life Science: God Made the Animals, Lesson 7.3 (grade K)
An animal that eats other animals. Lions, sharks and Tyrannosaurus rex are meat-eaters.
Kindergarten Life Science: God Made the Animals, Lesson 7.3 (grade K)
mechanical digestionEnglish
Breaking food into smaller pieces by chewing, churning and squeezing, without changing what it is made of.
Grade 5 Life Science: The Human Body, Lesson 5.1 (grade 5)
Breaking food into smaller pieces by chewing, churning and squeezing, without changing what it is made of.
Grade 5 Life Science: The Human Body, Lesson 5.1 (grade 5)
meeknessEnglish
Strength under control. In the Bible it is the manner in which a Christian is told to give a reason for his hope: firm about the truth, gentle with the person.
Grade 7 Earth Science: Earth History and the Flood, Lesson 8.3 (grade 7)
Strength under control. In the Bible it is the manner in which a Christian is told to give a reason for his hope: firm about the truth, gentle with the person.
Grade 7 Earth Science: Earth History and the Flood, Lesson 8.3 (grade 7)
melatoninEnglish
A chemical messenger the body makes mostly in the evening darkness that helps you feel sleepy. Bright light at night slows its release.
Grade 5 Life Science: The Human Body, Lesson 6.4 (grade 5) · Grade 11 Physical Education & Health, Lesson 1.1 (grade 11)
A chemical messenger the body makes mostly in the evening darkness that helps you feel sleepy. Bright light at night slows its release.
Grade 5 Life Science: The Human Body, Lesson 6.4 (grade 5) · Grade 11 Physical Education & Health, Lesson 1.1 (grade 11)
memorialEnglish
Something set up to help people remember an important day.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.4 (grade 1)
Something set up to help people remember an important day.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.4 (grade 1)
mercuryEnglish
A heavy, silvery metal that is liquid at room temperature. It is poisonous, so it must never be touched.
Grade 4 Earth Science: Weather and Water, Lesson 2.1 (grade 4)
A heavy, silvery metal that is liquid at room temperature. It is poisonous, so it must never be touched.
Grade 4 Earth Science: Weather and Water, Lesson 2.1 (grade 4)
meridianEnglish
An imaginary line on the globe running from the North Pole to the South Pole. Every place on one meridian has solar noon at the same moment.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.4 (grade 5) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 1.3 (grade 3) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 7.3 (grade 4) · +2 more
An imaginary line on the globe running from the North Pole to the South Pole. Every place on one meridian has solar noon at the same moment.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.4 (grade 5) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 1.3 (grade 3) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 7.3 (grade 4) · +2 more
mesophyllEnglish
The middle tissue of a leaf, packed with chloroplasts. Its lower, spongy part is full of air spaces, which is why leaves float.
Grade 7 Life Science: Cells and Microbes, Lesson 5.2 (grade 7)
The middle tissue of a leaf, packed with chloroplasts. Its lower, spongy part is full of air spaces, which is why leaves float.
Grade 7 Life Science: Cells and Microbes, Lesson 5.2 (grade 7)
MesosaurusEnglish
A small fossil reptile about one meter long that lived in fresh water. Its fossils are found only in southern Africa and eastern South America.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.2 (grade 6)
A small fossil reptile about one meter long that lived in fresh water. Its fossils are found only in southern Africa and eastern South America.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.2 (grade 6)
Messier objectEnglish
One of the star clusters, glowing clouds and galaxies on Charles Messier’s list, named with an M and a number, such as M45, the Pleiades.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.4 (grade 5)
One of the star clusters, glowing clouds and galaxies on Charles Messier’s list, named with an M and a number, such as M45, the Pleiades.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.4 (grade 5)
metamorphic rockEnglish
A rock that was changed into a new kind of rock by heat and pressure, without melting. The name comes from Greek words meaning “change of form.”
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.1 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.1 (grade 3)
A rock that was changed into a new kind of rock by heat and pressure, without melting. The name comes from Greek words meaning “change of form.”
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.1 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.1 (grade 3)
metamorphismEnglish
The change of an existing rock into a new rock by heat, pressure, and chemically active fluids, without melting.
High School Geology, Lesson 1.4 (grade 9–12)
The change of an existing rock into a new rock by heat, pressure, and chemically active fluids, without melting.
High School Geology, Lesson 1.4 (grade 9–12)
METAREnglish
The coded hourly weather observation from an airport: wind, visibility, clouds, temperature, dew point and altimeter setting. A TAF is the matching forecast for the airport.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.3 (grade 8)
The coded hourly weather observation from an airport: wind, visibility, clouds, temperature, dew point and altimeter setting. A TAF is the matching forecast for the airport.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.3 (grade 8)
meteorologistEnglish
A scientist who studies the atmosphere. Most forecasters hold a bachelor’s degree in meteorology or atmospheric science, which requires calculus and physics.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.4 (grade 8)
A scientist who studies the atmosphere. Most forecasters hold a bachelor’s degree in meteorology or atmospheric science, which requires calculus and physics.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.4 (grade 8)
methane (firedamp)English
A colorless, odorless gas (CH₄) that seeps out of coal seams. It explodes when it makes up about 5 to 15 percent of the air and meets a spark or flame.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.3 (grade 8)
A colorless, odorless gas (CH₄) that seeps out of coal seams. It explodes when it makes up about 5 to 15 percent of the air and meets a spark or flame.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.3 (grade 8)
methodological naturalismEnglish
The working rule, followed by most scientists, that science should explain things only by natural causes. Intelligent design writers argue that this rule should not forbid a conclusion of design.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.3 (grade 8)
The working rule, followed by most scientists, that science should explain things only by natural causes. Intelligent design writers argue that this rule should not forbid a conclusion of design.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.3 (grade 8)
methodsEnglish
The part of a report that says what you did and what tools you used: pacing, a floor plan at 1 : 500, a tape measure, copying signs by photograph.
Grade 7 Earth Science: Earth History and the Flood, Lesson 8.4 (grade 7)
The part of a report that says what you did and what tools you used: pacing, a floor plan at 1 : 500, a tape measure, copying signs by photograph.
Grade 7 Earth Science: Earth History and the Flood, Lesson 8.4 (grade 7)
microevolutionEnglish
Small changes in the traits of a population over generations, such as a shift in average beak size. These changes are observed and accepted by scientists of every view.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.1 (grade 8)
Small changes in the traits of a population over generations, such as a shift in average beak size. These changes are observed and accepted by scientists of every view.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.1 (grade 8)
microhabitatEnglish
A very small habitat inside a bigger one, such as the damp ground under a log or the bark of a tree.
Grade 3 Life Science: Plants and Animals Together, Lesson 5.4 (grade 3)
A very small habitat inside a bigger one, such as the damp ground under a log or the bark of a tree.
Grade 3 Life Science: Plants and Animals Together, Lesson 5.4 (grade 3)
micrometer (µm)English
One thousandth of a millimeter. A human hair is about 50 to 100 µm thick.
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.2 (grade 6) · Grade 7 Life Science: Cells and Microbes, Lesson 1.1 (grade 7) · Grade 7 Life Science: Cells and Microbes, Lesson 2.1 (grade 7) · +1 more
One thousandth of a millimeter. A human hair is about 50 to 100 µm thick.
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.2 (grade 6) · Grade 7 Life Science: Cells and Microbes, Lesson 1.1 (grade 7) · Grade 7 Life Science: Cells and Microbes, Lesson 2.1 (grade 7) · +1 more
microorganismEnglish
A living thing too small to see clearly without a microscope, such as a bacterium, a protist or a yeast cell. Also called a microbe.
Grade 7 Life Science: Cells and Microbes, Lesson 1.1 (grade 7)
A living thing too small to see clearly without a microscope, such as a bacterium, a protist or a yeast cell. Also called a microbe.
Grade 7 Life Science: Cells and Microbes, Lesson 1.1 (grade 7)
migratory restlessnessEnglish
The fidgety, hopping, wing-fluttering behavior of a caged bird at the season when it would be migrating. German scientists call it Zugunruhe.
Grade 6 Life Science: Animal Design and Behavior, Lesson 2.4 (grade 6)
The fidgety, hopping, wing-fluttering behavior of a caged bird at the season when it would be migrating. German scientists call it Zugunruhe.
Grade 6 Life Science: Animal Design and Behavior, Lesson 2.4 (grade 6)
Milankovitch cyclesEnglish
Slow changes in the earth’s orbit and tilt that mainstream scientists use to explain repeated ice ages. A museum word to recognize.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.3 (grade 7)
Slow changes in the earth’s orbit and tilt that mainstream scientists use to explain repeated ice ages. A museum word to recognize.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.3 (grade 7)
milkEnglish
The first food a mammal mother makes in her own body to feed her babies.
Grade 2 Life Science: Animal Families, Lesson 1.1 (grade 2)
The first food a mammal mother makes in her own body to feed her babies.
Grade 2 Life Science: Animal Families, Lesson 1.1 (grade 2)
milkweedEnglish
A wild plant with milky juice. It is the only food monarch caterpillars eat.
Grade 2 Life Science: Animal Families, Lesson 6.2 (grade 2)
A wild plant with milky juice. It is the only food monarch caterpillars eat.
Grade 2 Life Science: Animal Families, Lesson 6.2 (grade 2)
millibarEnglish
A unit for air pressure used on weather maps. Normal sea-level pressure is about 1013 millibars (29.92 inches of mercury).
Grade 4 Earth Science: Weather and Water, Lesson 2.2 (grade 4)
A unit for air pressure used on weather maps. Normal sea-level pressure is about 1013 millibars (29.92 inches of mercury).
Grade 4 Earth Science: Weather and Water, Lesson 2.2 (grade 4)
millimeters of mercury (mmHg)English
The unit doctors and biologists use for blood pressure: how high (in millimeters) the pressure could push a column of mercury. A column of blood 1 meter tall presses with about 77 mmHg.
Grade 7 Life Science: Cells and Microbes, Lesson 7.4 (grade 7)
The unit doctors and biologists use for blood pressure: how high (in millimeters) the pressure could push a column of mercury. A column of blood 1 meter tall presses with about 77 mmHg.
Grade 7 Life Science: Cells and Microbes, Lesson 7.4 (grade 7)
mineralEnglish
A natural, nonliving solid, like salt or the stuff limestone is made of. Water can carry some minerals and leave them behind.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.2 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.1 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.4 (grade 3) · +3 more
A natural, nonliving solid, like salt or the stuff limestone is made of. Water can carry some minerals and leave them behind.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.2 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.1 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.4 (grade 3) · +3 more
miracleEnglish
A wonderful thing that only God can do, beyond the usual way things work.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.4 (grade 1)
A wonderful thing that only God can do, beyond the usual way things work.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.4 (grade 1)
mitochondrionEnglish
The organelle where most of cellular respiration happens; often called the powerhouse of the cell. The plural is mitochondria.
Grade 7 Life Science: Cells and Microbes, Lesson 5.3 (grade 7)
The organelle where most of cellular respiration happens; often called the powerhouse of the cell. The plural is mitochondria.
Grade 7 Life Science: Cells and Microbes, Lesson 5.3 (grade 7)
mitochondrion (plural: mitochondria)English
The organelle that releases the energy stored in food, using oxygen, in the process called cellular respiration.
Grade 7 Life Science: Cells and Microbes, Lesson 2.2 (grade 7)
The organelle that releases the energy stored in food, using oxygen, in the process called cellular respiration.
Grade 7 Life Science: Cells and Microbes, Lesson 2.2 (grade 7)
Modified Mercalli intensityEnglish
A scale from I to XII describing how strong the shaking felt and what it damaged at a particular place.
High School Geology, Lesson 2.2 (grade 9–12)
A scale from I to XII describing how strong the shaking felt and what it damaged at a particular place.
High School Geology, Lesson 2.2 (grade 9–12)
MohoEnglish
Short for the Mohorovičić discontinuity: the boundary between the crust and the mantle, where seismic waves suddenly speed up.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.2 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 2.1 (grade 6)
Short for the Mohorovičić discontinuity: the boundary between the crust and the mantle, where seismic waves suddenly speed up.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.2 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 2.1 (grade 6)
Mohs scaleEnglish
A list of ten minerals from softest (1, talc) to hardest (10, diamond), made by Friedrich Mohs in 1812.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.1 (grade 3)
A list of ten minerals from softest (1, talc) to hardest (10, diamond), made by Friedrich Mohs in 1812.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.1 (grade 3)
molarEnglish
A wide cheek tooth in the back of the mouth used for crushing and grinding. The premolars, just in front of the molars, help slice and crush.
Grade 4 Life Science: Classification, Lesson 5.1 (grade 4)
A wide cheek tooth in the back of the mouth used for crushing and grinding. The premolars, just in front of the molars, help slice and crush.
Grade 4 Life Science: Classification, Lesson 5.1 (grade 4)
mold and castEnglish
A mold is a hollow left in rock where a shell or bone used to be. A cast is what forms when that hollow fills with mud or minerals and makes a copy of the shape.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.4 (grade 3) · Grade 7 Earth Science: Earth History and the Flood, Lesson 1.1 (grade 7)
A mold is a hollow left in rock where a shell or bone used to be. A cast is what forms when that hollow fills with mud or minerals and makes a copy of the shape.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.4 (grade 3) · Grade 7 Earth Science: Earth History and the Flood, Lesson 1.1 (grade 7)
moltingEnglish
Shedding the old exoskeleton so the animal can grow. The new, soft exoskeleton stretches before it hardens. Scientists also call it ecdysis.
Grade 7 Life Science: Cells and Microbes, Lesson 7.3 (grade 7)
Shedding the old exoskeleton so the animal can grow. The new, soft exoskeleton stretches before it hardens. Scientists also call it ecdysis.
Grade 7 Life Science: Cells and Microbes, Lesson 7.3 (grade 7)
moment magnitude (Mw)English
The modern magnitude scale, calculated from the seismic moment, used by the USGS for large earthquakes.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.2 (grade 6) · High School Geology, Lesson 2.2 (grade 9–12)
The modern magnitude scale, calculated from the seismic moment, used by the USGS for large earthquakes.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.2 (grade 6) · High School Geology, Lesson 2.2 (grade 9–12)
monarchEnglish
A big orange and black butterfly. It is an insect with six legs and four wings.
Grade 2 Life Science: Animal Families, Lesson 6.2 (grade 2)
A big orange and black butterfly. It is an insect with six legs and four wings.
Grade 2 Life Science: Animal Families, Lesson 6.2 (grade 2)
monitor lizardEnglish
A family of large lizards including the Komodo dragon, which grows to about 3 m, and the extinct Australian Megalania, estimated at 5 m or more.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.3 (grade 7) · Explore Animals · Expert, Stop 3.2 (Ages 14+) · Explore Animals · Ranger, Stop 3.2 (Ages 10–13) · +1 more
A family of large lizards including the Komodo dragon, which grows to about 3 m, and the extinct Australian Megalania, estimated at 5 m or more.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.3 (grade 7) · Explore Animals · Expert, Stop 3.2 (Ages 14+) · Explore Animals · Ranger, Stop 3.2 (Ages 10–13) · +1 more
monkeyEnglish
A primate that usually has a tail and runs along the tops of branches on all fours. Baboons, capuchins and spider monkeys are monkeys.
Grade 4 Life Science: Classification, Lesson 5.3 (grade 4)
A primate that usually has a tail and runs along the tops of branches on all fours. Baboons, capuchins and spider monkeys are monkeys.
Grade 4 Life Science: Classification, Lesson 5.3 (grade 4)
monoclineEnglish
A step-like fold in otherwise flat layers, such as the Kaibab monocline on the canyon’s east side.
High School Geology, Lesson 6.3 (grade 9–12)
A step-like fold in otherwise flat layers, such as the Kaibab monocline on the canyon’s east side.
High School Geology, Lesson 6.3 (grade 9–12)
monotremeEnglish
A mammal that lays eggs. The platypus and the echidnas are the only monotremes living today.
Grade 4 Life Science: Classification, Lesson 2.4 (grade 4) · Grade 4 Life Science: Classification, Lesson 5.2 (grade 4)
A mammal that lays eggs. The platypus and the echidnas are the only monotremes living today.
Grade 4 Life Science: Classification, Lesson 2.4 (grade 4) · Grade 4 Life Science: Classification, Lesson 5.2 (grade 4)
moonEnglish
The big round ball of rock that travels around the earth. God made it to give light by night.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.4 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 5.3 (grade K)
The big round ball of rock that travels around the earth. God made it to give light by night.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.4 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 5.3 (grade K)
Moon illusionEnglish
The trick of the eye that makes the Moon look bigger near the horizon than high in the sky, though it is really the same size.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.3 (grade 5)
The trick of the eye that makes the Moon look bigger near the horizon than high in the sky, though it is really the same size.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.3 (grade 5)
moon phaseEnglish
The shape of the lit-up part of the moon that we see on one night.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.1 (grade 1)
The shape of the lit-up part of the moon that we see on one night.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.1 (grade 1)
moonlightEnglish
Sunlight that bounces off the moon and comes down to us.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.4 (grade 1)
Sunlight that bounces off the moon and comes down to us.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.4 (grade 1)
moraineEnglish
A long pile of rocks, sand and gravel that a glacier pushed or dropped.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.2 (grade 2) · Grade 7 Earth Science: Earth History and the Flood, Lesson 5.1 (grade 7) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 4.4 (grade 6) · +3 more
A long pile of rocks, sand and gravel that a glacier pushed or dropped.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.2 (grade 2) · Grade 7 Earth Science: Earth History and the Flood, Lesson 5.1 (grade 7) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 4.4 (grade 6) · +3 more
Morrison FormationEnglish
A museum word: the name given to the broad band of mudstone and sandstone, stretching across much of the western United States, in which most famous American dinosaur quarries lie.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.2 (grade 6) · Explore Dinosaurs · Expert, Stop 2.6 (Ages 14+) · Explore Dinosaurs · Ranger, Stop 1.3 (Ages 10–13)
A museum word: the name given to the broad band of mudstone and sandstone, stretching across much of the western United States, in which most famous American dinosaur quarries lie.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.2 (grade 6) · Explore Dinosaurs · Expert, Stop 2.6 (Ages 14+) · Explore Dinosaurs · Ranger, Stop 1.3 (Ages 10–13)
mortality rateEnglish
The fraction of people in a group who die in a given time, often written as a percent or as deaths per 1,000.
Grade 7 Life Science: Cells and Microbes, Lesson 4.1 (grade 7)
The fraction of people in a group who die in a given time, often written as a percent or as deaths per 1,000.
Grade 7 Life Science: Cells and Microbes, Lesson 4.1 (grade 7)
mountainEnglish
Land that rises high above the land around it, with steep sides and a top.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.1 (grade 2) · Grade 1 Geography: Maps and Journeys, Lesson 3.1 (grade 1) · Grade 1 Geography: Maps and Journeys, Lesson 5.4 (grade 1) · +1 more
Land that rises high above the land around it, with steep sides and a top.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.1 (grade 2) · Grade 1 Geography: Maps and Journeys, Lesson 3.1 (grade 1) · Grade 1 Geography: Maps and Journeys, Lesson 5.4 (grade 1) · +1 more
mountain beltEnglish
A long chain of folded and faulted rock, such as the Appalachians. Some belts end at a coast and seem to continue on another continent.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.2 (grade 6)
A long chain of folded and faulted rock, such as the Appalachians. Some belts end at a coast and seem to continue on another continent.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.2 (grade 6)
mountain rangeEnglish
A long row of mountains standing together.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.2 (grade 2) · Grade 2 Geography: Our Country, Coast to Coast, Lesson 2.4 (grade 2) · Grade 2 Geography: Our Country, Coast to Coast, Lesson 4.1 (grade 2) · +3 more
A long row of mountains standing together.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.2 (grade 2) · Grade 2 Geography: Our Country, Coast to Coast, Lesson 2.4 (grade 2) · Grade 2 Geography: Our Country, Coast to Coast, Lesson 4.1 (grade 2) · +3 more
mouthEnglish
The place where a river ends and pours into the sea or a big lake.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.1 (grade 1) · Grade 4 Earth Science: Weather and Water, Lesson 6.3 (grade 4) · Grade 1 Geography: Maps and Journeys, Lesson 4.3 (grade 1) · +3 more
The place where a river ends and pours into the sea or a big lake.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.1 (grade 1) · Grade 4 Earth Science: Weather and Water, Lesson 6.3 (grade 4) · Grade 1 Geography: Maps and Journeys, Lesson 4.3 (grade 1) · +3 more
mRNA (messenger RNA)English
A single-stranded working copy of a gene that carries the message from the DNA in the nucleus to a ribosome. RNA uses uracil (U) in place of thymine (T).
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.3 (grade 8)
A single-stranded working copy of a gene that carries the message from the DNA in the nucleus to a ribosome. RNA uses uracil (U) in place of thymine (T).
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.3 (grade 8)
MSHAEnglish
The Mine Safety and Health Administration, created by the Federal Mine Safety and Health Act of 1977. Its inspectors must visit every underground mine four times a year and every surface mine twice.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.3 (grade 8)
The Mine Safety and Health Administration, created by the Federal Mine Safety and Health Act of 1977. Its inspectors must visit every underground mine four times a year and every surface mine twice.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.3 (grade 8)
mucusEnglish
A sticky, slippery liquid that lines the nose and airways and traps dust, smoke particles and germs.
Grade 5 Life Science: The Human Body, Lesson 4.4 (grade 5)
A sticky, slippery liquid that lines the nose and airways and traps dust, smoke particles and germs.
Grade 5 Life Science: The Human Body, Lesson 4.4 (grade 5)
mudEnglish
Wet, soft dirt. Feet sink into it and leave a print.
Grade 2 Earth Science: The Earth's Surface, Lesson 7.2 (grade 2) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.3 (grade K) · Kindergarten Gardening & Animals, Lesson 3.4 (grade K)
Wet, soft dirt. Feet sink into it and leave a print.
Grade 2 Earth Science: The Earth's Surface, Lesson 7.2 (grade 2) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.3 (grade K) · Kindergarten Gardening & Animals, Lesson 3.4 (grade K)
mudflowEnglish
A fast, rushing river of mud, water and rocks.
Grade 2 Earth Science: The Earth's Surface, Lesson 8.3 (grade 2)
A fast, rushing river of mud, water and rocks.
Grade 2 Earth Science: The Earth's Surface, Lesson 8.3 (grade 2)
Müllerian mimicryEnglish
When two or more bad-tasting or dangerous animals share a similar warning pattern, so predators learn to avoid all of them faster. Named for Fritz Müller.
Grade 6 Life Science: Animal Design and Behavior, Lesson 4.3 (grade 6)
When two or more bad-tasting or dangerous animals share a similar warning pattern, so predators learn to avoid all of them faster. Named for Fritz Müller.
Grade 6 Life Science: Animal Design and Behavior, Lesson 4.3 (grade 6)
multicellularEnglish
Made of many cells that work together, such as an oak tree, a frog or a person.
Grade 7 Life Science: Cells and Microbes, Lesson 2.1 (grade 7)
Made of many cells that work together, such as an oak tree, a frog or a person.
Grade 7 Life Science: Cells and Microbes, Lesson 2.1 (grade 7)
muscleEnglish
A body tissue that can contract (get shorter) to pull on bones or squeeze organs.
Grade 5 Life Science: The Human Body, Lesson 2.4 (grade 5) · Grade 2 Physical Education & Health, Lesson 1.2 (grade 2) · Grade 2 Physical Education & Health, Lesson 4.1 (grade 2) · +3 more
A body tissue that can contract (get shorter) to pull on bones or squeeze organs.
Grade 5 Life Science: The Human Body, Lesson 2.4 (grade 5) · Grade 2 Physical Education & Health, Lesson 1.2 (grade 2) · Grade 2 Physical Education & Health, Lesson 4.1 (grade 2) · +3 more
muscle pairEnglish
Two muscles that pull a bone in opposite directions, such as the biceps (bends the elbow) and triceps (straightens it).
Grade 5 Life Science: The Human Body, Lesson 2.4 (grade 5)
Two muscles that pull a bone in opposite directions, such as the biceps (bends the elbow) and triceps (straightens it).
Grade 5 Life Science: The Human Body, Lesson 2.4 (grade 5)
museumEnglish
A building where specimens and other treasures are kept, cared for, labeled and shown to the public.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 8.2 (grade 3) · Explore Dinosaurs, Stop 2.4 (Ages 7–9) · Explore Dinosaurs, Stop 4.8 (Ages 7–9) · +3 more
A building where specimens and other treasures are kept, cared for, labeled and shown to the public.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 8.2 (grade 3) · Explore Dinosaurs, Stop 2.4 (Ages 7–9) · Explore Dinosaurs, Stop 4.8 (Ages 7–9) · +3 more
mustard seedEnglish
A tiny round seed, about the size of a dot. It grows into a tall plant with yellow flowers.
Kindergarten Life Science: God Made the Animals, Lesson 5.4 (grade K)
A tiny round seed, about the size of a dot. It grows into a tall plant with yellow flowers.
Kindergarten Life Science: God Made the Animals, Lesson 5.4 (grade K)
mutationEnglish
A change in the DNA sequence of a gene. Some mutations have no effect, some are harmful and a few give a trait breeders want, such as short legs.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.2 (grade 8) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.2 (grade 8)
A change in the DNA sequence of a gene. Some mutations have no effect, some are harmful and a few give a trait breeders want, such as short legs.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.2 (grade 8) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.2 (grade 8)
mycologistEnglish
A scientist who studies fungi.
Grade 7 Life Science: Cells and Microbes, Lesson 6.4 (grade 7)
A scientist who studies fungi.
Grade 7 Life Science: Cells and Microbes, Lesson 6.4 (grade 7)
mycotoxinEnglish
A poison made by some molds. For example, a mold called Aspergillus flavus can make aflatoxin on poorly stored grain and peanuts.
Grade 7 Life Science: Cells and Microbes, Lesson 6.2 (grade 7)
A poison made by some molds. For example, a mold called Aspergillus flavus can make aflatoxin on poorly stored grain and peanuts.
Grade 7 Life Science: Cells and Microbes, Lesson 6.2 (grade 7)
N
nanometer (nm)English
One millionth of a millimeter. 1 mm = 1,000 µm = 1,000,000 nm.
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.3 (grade 6)
One millionth of a millimeter. 1 mm = 1,000 µm = 1,000,000 nm.
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.3 (grade 6)
narrative proseEnglish
Plain reporting language with names, places, dates and measurements, as opposed to the parallel lines and word pictures of Hebrew poetry.
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.1 (grade 7)
Plain reporting language with names, places, dates and measurements, as opposed to the parallel lines and word pictures of Hebrew poetry.
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.1 (grade 7)
National Weather Service (NWS)English
The United States government agency, part of NOAA, that observes the weather, issues forecasts and warns the public. It began in 1870 under the Army Signal Service and took its present name in 1970.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.1 (grade 8)
The United States government agency, part of NOAA, that observes the weather, issues forecasts and warns the public. It began in 1870 under the Army Signal Service and took its present name in 1970.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.1 (grade 8)
native metalEnglish
A metal found pure in nature, not locked inside an ore. Gold nuggets are native gold.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.2 (grade 3)
A metal found pure in nature, not locked inside an ore. Gold nuggets are native gold.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.2 (grade 3)
natural gasEnglish
Mostly methane (CH₄), the lightest hydrocarbon. It is found above oil in traps or on its own, is moved by pipeline, and is burned for heat and electricity or turned into fertilizer.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.4 (grade 8)
Mostly methane (CH₄), the lightest hydrocarbon. It is found above oil in traps or on its own, is moved by pipeline, and is burned for heat and electricity or turned into fertilizer.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.4 (grade 8)
natural leveeEnglish
A low ridge of sand and mud that a river builds along its own banks when floods drop their heaviest sediment right next to the channel.
Grade 4 Earth Science: Weather and Water, Lesson 6.2 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 4.3 (grade 6)
A low ridge of sand and mud that a river builds along its own banks when floods drop their heaviest sediment right next to the channel.
Grade 4 Earth Science: Weather and Water, Lesson 6.2 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 4.3 (grade 6)
natural periodEnglish
The time a building takes to sway once back and forth on its own; roughly one tenth of a second per story.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.1 (grade 6)
The time a building takes to sway once back and forth on its own; roughly one tenth of a second per story.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.1 (grade 6)
natural theologyEnglish
Learning about God from what can be observed in nature, as opposed to learning about Him from the Bible. Paley’s book took this as its title.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.1 (grade 8)
Learning about God from what can be observed in nature, as opposed to learning about Him from the Bible. Paley’s book took this as its title.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.1 (grade 8)
neap tideEnglish
A small tide range that comes near first and third quarter, when the Sun and Moon pull at right angles to each other.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.4 (grade 5) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 7.3 (grade 6)
A small tide range that comes near first and third quarter, when the Sun and Moon pull at right angles to each other.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.4 (grade 5) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 7.3 (grade 6)
neck bonesEnglish
The small bones, one after another, that make up the neck. You have 7. So does a giraffe.
Grade 1 Life Science: Animal Homes and Habits, Lesson 7.2 (grade 1)
The small bones, one after another, that make up the neck. You have 7. So does a giraffe.
Grade 1 Life Science: Animal Homes and Habits, Lesson 7.2 (grade 1)
nerveEnglish
A cable-like bundle of long neuron fibers that carries messages between the brain or spinal cord and the rest of the body.
Grade 5 Life Science: The Human Body, Lesson 6.1 (grade 5)
A cable-like bundle of long neuron fibers that carries messages between the brain or spinal cord and the rest of the body.
Grade 5 Life Science: The Human Body, Lesson 6.1 (grade 5)
nestEnglish
A place an animal makes to lay its eggs and keep them safe.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.4 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.1 (grade K) · Explore Animals, Stop 2.8 (Ages 7–9) · +3 more
A place an animal makes to lay its eggs and keep them safe.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.4 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.1 (grade K) · Explore Animals, Stop 2.8 (Ages 7–9) · +3 more
nesting horizonEnglish
A single layer of rock in which many nests of the same kind of egg are found, read as one nesting ground.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.2 (grade 7)
A single layer of rock in which many nests of the same kind of egg are found, read as one nesting ground.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.2 (grade 7)
new moonEnglish
When the lit-up side of the moon faces away from us, so we cannot see the moon at all.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.1 (grade 1)
When the lit-up side of the moon faces away from us, so we cannot see the moon at all.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.1 (grade 1)
newtEnglish
A kind of salamander that spends much of its life in ponds and streams.
Grade 2 Life Science: Animal Families, Lesson 4.3 (grade 2)
A kind of salamander that spends much of its life in ponds and streams.
Grade 2 Life Science: Animal Families, Lesson 4.3 (grade 2)
nicotineEnglish
A drug in tobacco (and in most e-cigarettes) that is addictive, meaning the body comes to crave it so that it is very hard to stop using.
Grade 5 Life Science: The Human Body, Lesson 4.4 (grade 5)
A drug in tobacco (and in most e-cigarettes) that is addictive, meaning the body comes to crave it so that it is very hard to stop using.
Grade 5 Life Science: The Human Body, Lesson 4.4 (grade 5)
nimbusEnglish
Latin for “a rain cloud.” In cloud names, nimbo- or -nimbus means the cloud brings rain or snow.
Grade 4 Earth Science: Weather and Water, Lesson 3.1 (grade 4)
Latin for “a rain cloud.” In cloud names, nimbo- or -nimbus means the cloud brings rain or snow.
Grade 4 Earth Science: Weather and Water, Lesson 3.1 (grade 4)
NisanEnglish
The first month of the Hebrew religious year, called Abib in Exodus. It begins at a new moon in the spring.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.4 (grade 5)
The first month of the Hebrew religious year, called Abib in Exodus. It begins at a new moon in the spring.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.4 (grade 5)
nonconformityEnglish
An unconformity where sedimentary layers rest on crystalline rock such as granite or schist, as at the Great Unconformity.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.2 (grade 7)
An unconformity where sedimentary layers rest on crystalline rock such as granite or schist, as at the Great Unconformity.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.2 (grade 7)
non-point sourceEnglish
Pollution that enters water from many diffuse places across the landscape, such as fertilizer from farm fields, as opposed to a point source such as a single leaking tank.
High School Geology, Lesson 4.4 (grade 9–12)
Pollution that enters water from many diffuse places across the landscape, such as fertilizer from farm fields, as opposed to a point source such as a single leaking tank.
High School Geology, Lesson 4.4 (grade 9–12)
nonvascular plantEnglish
A plant with no tubes inside to carry water and food. Mosses are nonvascular, so they stay small and soak up water like a sponge.
Grade 4 Life Science: Classification, Lesson 6.1 (grade 4)
A plant with no tubes inside to carry water and food. Mosses are nonvascular, so they stay small and soak up water like a sponge.
Grade 4 Life Science: Classification, Lesson 6.1 (grade 4)
noonEnglish
The middle of the day, when the sun is highest in the sky and shadows are shortest.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 5.2 (grade K) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.4 (grade K) · Explore Travel and Faraway Places, Stop 1.5 (Ages 7–9) · +1 more
The middle of the day, when the sun is highest in the sky and shadows are shortest.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 5.2 (grade K) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.4 (grade K) · Explore Travel and Faraway Places, Stop 1.5 (Ages 7–9) · +1 more
noon Sun heightEnglish
How many degrees above the horizon the Sun stands at midday, when it is highest. Straight overhead is 90°.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.2 (grade 5)
How many degrees above the horizon the Sun stands at midday, when it is highest. Straight overhead is 90°.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.2 (grade 5)
nor’easterEnglish
A strong storm along the East Coast of the United States whose winds blow in from the northeast, off the ocean.
Grade 4 Earth Science: Weather and Water, Lesson 4.3 (grade 4) · Explore Great Battles · Ranger, Stop 3.5 (Ages 10–13)
A strong storm along the East Coast of the United States whose winds blow in from the northeast, off the ocean.
Grade 4 Earth Science: Weather and Water, Lesson 4.3 (grade 4) · Explore Great Battles · Ranger, Stop 3.5 (Ages 10–13)
normal, reverse and strike-slip faultsEnglish
In a normal fault the hanging wall drops (tension). In a reverse or thrust fault the hanging wall rises (compression). In a strike-slip fault the blocks slide sideways (shear).
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.1 (grade 6)
In a normal fault the hanging wall drops (tension). In a reverse or thrust fault the hanging wall rises (compression). In a strike-slip fault the blocks slide sideways (shear).
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.1 (grade 6)
North Atlantic CurrentEnglish
The continuation of the Gulf Stream as it carries warm water across the Atlantic toward Europe.
Grade 4 Earth Science: Weather and Water, Lesson 7.4 (grade 4)
The continuation of the Gulf Stream as it carries warm water across the Atlantic toward Europe.
Grade 4 Earth Science: Weather and Water, Lesson 7.4 (grade 4)
North StarEnglish
A star that stays in almost the same place all night, in the north. The Big Dipper helps us find it.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 5.4 (grade K) · Explore Heroines of History and Faith, Stop 4.3 (Ages 7–9)
A star that stays in almost the same place all night, in the north. The Big Dipper helps us find it.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 5.4 (grade K) · Explore Heroines of History and Faith, Stop 4.3 (Ages 7–9)
north windEnglish
A wind that comes from the north and blows toward the south. Winds are named for where they come from.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.2 (grade 1)
A wind that comes from the north and blows toward the south. Winds are named for where they come from.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.2 (grade 1)
nostrilsEnglish
The holes in the nose that air goes in and out of.
Grade 2 Life Science: Animal Families, Lesson 3.3 (grade 2)
The holes in the nose that air goes in and out of.
Grade 2 Life Science: Animal Families, Lesson 3.3 (grade 2)
novaEnglish
From the Latin word for “new”: a star that suddenly grows much brighter, so that it looks like a new star where none was seen before.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.4 (grade 5)
From the Latin word for “new”: a star that suddenly grows much brighter, so that it looks like a new star where none was seen before.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.4 (grade 5)
nucleotideEnglish
One building block of DNA: a sugar (deoxyribose), a phosphate group and one of four bases: adenine (A), thymine (T), guanine (G) or cytosine (C).
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.1 (grade 8)
One building block of DNA: a sugar (deoxyribose), a phosphate group and one of four bases: adenine (A), thymine (T), guanine (G) or cytosine (C).
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.1 (grade 8)
nucleusEnglish
The control center of the cell, usually a round body near the middle. It holds the cell’s instructions.
Grade 5 Life Science: The Human Body, Lesson 1.2 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 2.1 (grade 7) · Grade 7 Life Science: Cells and Microbes, Lesson 2.2 (grade 7) · +1 more
The control center of the cell, usually a round body near the middle. It holds the cell’s instructions.
Grade 5 Life Science: The Human Body, Lesson 1.2 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 2.1 (grade 7) · Grade 7 Life Science: Cells and Microbes, Lesson 2.2 (grade 7) · +1 more
nutrientsEnglish
The materials in soil that plants need to grow strong and healthy.
Grade 3 Life Science: Plants and Animals Together, Lesson 4.4 (grade 3)
The materials in soil that plants need to grow strong and healthy.
Grade 3 Life Science: Plants and Animals Together, Lesson 4.4 (grade 3)
O
objective lensEnglish
The big front lens of a telescope. It gathers light and makes a small, upside-down image inside the tube.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.1 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 1.2 (grade 7)
The big front lens of a telescope. It gathers light and makes a small, upside-down image inside the tube.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.1 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 1.2 (grade 7)
observatoryEnglish
A building or group of buildings made for watching and measuring the sky, usually with large telescopes.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.3 (grade 5) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 1.3 (grade 3) · Grade 5 Geography: Explorers, Navigators and Missionaries, Lesson 5.1 (grade 5)
A building or group of buildings made for watching and measuring the sky, usually with large telescopes.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.3 (grade 5) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 1.3 (grade 3) · Grade 5 Geography: Explorers, Navigators and Missionaries, Lesson 5.1 (grade 5)
observerEnglish
A person who carefully watches, measures and writes down what happens, the same way every time.
Grade 4 Earth Science: Weather and Water, Lesson 9.1 (grade 4)
A person who carefully watches, measures and writes down what happens, the same way every time.
Grade 4 Earth Science: Weather and Water, Lesson 9.1 (grade 4)
observing logEnglish
A record of each observing session: date, time, place, sky conditions, instrument, what you saw and a sketch.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.4 (grade 5)
A record of each observing session: date, time, place, sky conditions, instrument, what you saw and a sketch.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.4 (grade 5)
obsidianEnglish
A shiny, dark lava rock that looks like black glass. It forms when lava cools so fast that it turns to glass.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.3 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.3 (grade 3)
A shiny, dark lava rock that looks like black glass. It forms when lava cools so fast that it turns to glass.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.3 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.3 (grade 3)
occluded frontEnglish
A front formed when a fast cold front catches up with a warm front. Map symbol: a purple line with triangles and half circles on the same side.
Grade 4 Earth Science: Weather and Water, Lesson 5.3 (grade 4)
A front formed when a fast cold front catches up with a warm front. Map symbol: a purple line with triangles and half circles on the same side.
Grade 4 Earth Science: Weather and Water, Lesson 5.3 (grade 4)
ocean currentEnglish
A steady stream of water that moves through the ocean in a certain direction, like a river in the sea.
Grade 4 Earth Science: Weather and Water, Lesson 7.1 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 7.1 (grade 6) · Grade 7 Geography: Regions of the World, Lesson 2.2 (grade 7)
A steady stream of water that moves through the ocean in a certain direction, like a river in the sea.
Grade 4 Earth Science: Weather and Water, Lesson 7.1 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 7.1 (grade 6) · Grade 7 Geography: Regions of the World, Lesson 2.2 (grade 7)
offsetEnglish
The distance a layer has been shifted across a fault, measured from its position on one side to its position on the other.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.4 (grade 7)
The distance a layer has been shifted across a fault, measured from its position on one side to its position on the other.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.4 (grade 7)
oktaEnglish
One eighth of the sky. Weather observers measure cloud cover from 0 oktas (clear) to 8 oktas (completely covered).
Grade 4 Earth Science: Weather and Water, Lesson 3.4 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 9.2 (grade 4)
One eighth of the sky. Weather observers measure cloud cover from 0 oktas (clear) to 8 oktas (completely covered).
Grade 4 Earth Science: Weather and Water, Lesson 3.4 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 9.2 (grade 4)
Old Red SandstoneEnglish
A thick body of red sandstone and shale in Scotland, Wales and England, famous for fossil fish; a museum word for the Devonian rocks Hugh Miller quarried and wrote about.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.2 (grade 8)
A thick body of red sandstone and shale in Scotland, Wales and England, famous for fossil fish; a museum word for the Devonian rocks Hugh Miller quarried and wrote about.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.2 (grade 8)
open circulatory systemEnglish
A system in which the blood-like fluid (hemolymph) is pumped by a tube-shaped heart along the back and then flows loosely around the organs instead of staying inside vessels.
Grade 7 Life Science: Cells and Microbes, Lesson 7.3 (grade 7)
A system in which the blood-like fluid (hemolymph) is pumped by a tube-shaped heart along the back and then flows loosely around the organs instead of staying inside vessels.
Grade 7 Life Science: Cells and Microbes, Lesson 7.3 (grade 7)
open-pit mineEnglish
A surface mine dug downward as a huge bowl of stepped ledges (benches), used when the ore body is large and near the surface.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.2 (grade 8)
A surface mine dug downward as a huge bowl of stepped ledges (benches), used when the ore body is large and near the surface.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.2 (grade 8)
operculumEnglish
The bony flap that covers and protects the gills of a bony fish. It opens and closes to pump water out over the gills.
Grade 7 Life Science: Cells and Microbes, Lesson 7.1 (grade 7)
The bony flap that covers and protects the gills of a bony fish. It opens and closes to pump water out over the gills.
Grade 7 Life Science: Cells and Microbes, Lesson 7.1 (grade 7)
opposable thumbEnglish
A thumb that can swing across the palm to touch the tips of the other fingers, so the hand can pinch and grip.
Grade 4 Life Science: Classification, Lesson 5.3 (grade 4)
A thumb that can swing across the palm to touch the tips of the other fingers, so the hand can pinch and grip.
Grade 4 Life Science: Classification, Lesson 5.3 (grade 4)
optic nerveEnglish
The thick bundle of nerve fibers that carries signals from the retina to the brain.
Grade 5 Life Science: The Human Body, Lesson 7.1 (grade 5) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.2 (grade 8)
The thick bundle of nerve fibers that carries signals from the retina to the brain.
Grade 5 Life Science: The Human Body, Lesson 7.1 (grade 5) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.2 (grade 8)
oral traditionEnglish
Stories, songs and genealogies passed down by speaking and memory rather than writing.
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.3 (grade 7)
Stories, songs and genealogies passed down by speaking and memory rather than writing.
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.3 (grade 7)
orbitEnglish
The curved path one body in space follows around another, like the earth’s path around the sun.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.3 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.1 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.1 (grade 5) · +3 more
The curved path one body in space follows around another, like the earth’s path around the sun.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.3 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.1 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.1 (grade 5) · +3 more
oreEnglish
A rock with enough metal in it to be worth digging out. Hematite is an iron ore.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.2 (grade 3) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.2 (grade 8) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 4.1 (grade 4) · +2 more
A rock with enough metal in it to be worth digging out. Hematite is an iron ore.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.2 (grade 3) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.2 (grade 8) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 4.1 (grade 4) · +2 more
ore gradeEnglish
How much valuable metal a rock contains, often given as grams per tonne (g/t) for gold or as a percent for copper.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.1 (grade 8) · Geography and Commerce: Sea Lanes, Straits and Trade Routes, Lesson 4.5 (grade 9–12)
How much valuable metal a rock contains, often given as grams per tonne (g/t) for gold or as a percent for copper.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.1 (grade 8) · Geography and Commerce: Sea Lanes, Straits and Trade Routes, Lesson 4.5 (grade 9–12)
organEnglish
A body part made of two or more kinds of tissue working together to do a job, such as the heart, stomach, brain or skin.
Grade 5 Life Science: The Human Body, Lesson 1.3 (grade 5)
A body part made of two or more kinds of tissue working together to do a job, such as the heart, stomach, brain or skin.
Grade 5 Life Science: The Human Body, Lesson 1.3 (grade 5)
organ systemEnglish
A group of organs working together for one big task, such as the digestive system, which breaks down food.
Grade 5 Life Science: The Human Body, Lesson 1.3 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 8.4 (grade 7)
A group of organs working together for one big task, such as the digestive system, which breaks down food.
Grade 5 Life Science: The Human Body, Lesson 1.3 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 8.4 (grade 7)
organelleEnglish
A tiny structure inside a cell that does a particular job, as an organ does in the body. The word means “little organ.”
Grade 7 Life Science: Cells and Microbes, Lesson 2.2 (grade 7)
A tiny structure inside a cell that does a particular job, as an organ does in the body. The word means “little organ.”
Grade 7 Life Science: Cells and Microbes, Lesson 2.2 (grade 7)
organismEnglish
A whole living thing, such as a person, a dog or an oak tree.
Grade 5 Life Science: The Human Body, Lesson 1.3 (grade 5)
A whole living thing, such as a person, a dog or an oak tree.
Grade 5 Life Science: The Human Body, Lesson 1.3 (grade 5)
original horizontalityEnglish
Steno’s rule that sediment settling from water forms layers that are flat (level) or nearly so; layers that are now tilted or folded were moved after they formed.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.3 (grade 7)
Steno’s rule that sediment settling from water forms layers that are flat (level) or nearly so; layers that are now tilted or folded were moved after they formed.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.3 (grade 7)
OrionEnglish
A bright constellation shaped like a hunter, with three stars in a row for his belt. In the Hebrew of Job it is called Kesil.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.2 (grade 5)
A bright constellation shaped like a hunter, with three stars in a row for his belt. In the Hebrew of Job it is called Kesil.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.2 (grade 5)
ornithischianEnglish
A “bird-hipped” dinosaur, whose pubis bone pointed backward. All ornithischians were plant eaters with a beak at the front of their jaws.
Grade 4 Life Science: Classification, Lesson 7.4 (grade 4)
A “bird-hipped” dinosaur, whose pubis bone pointed backward. All ornithischians were plant eaters with a beak at the front of their jaws.
Grade 4 Life Science: Classification, Lesson 7.4 (grade 4)
ornithologistEnglish
A scientist who studies birds. The study of birds is called ornithology.
Grade 4 Life Science: Classification, Lesson 4.1 (grade 4)
A scientist who studies birds. The study of birds is called ornithology.
Grade 4 Life Science: Classification, Lesson 4.1 (grade 4)
orreryEnglish
A machine with gears that shows the planets moving around the Sun. Its sizes and distances are almost never to scale.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.2 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.4 (grade 5)
A machine with gears that shows the planets moving around the Sun. Its sizes and distances are almost never to scale.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.2 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.4 (grade 5)
ossiclesEnglish
The three tiny bones of the middle ear (the hammer, anvil and stirrup) that carry vibrations from the eardrum to the inner ear.
Grade 5 Life Science: The Human Body, Lesson 7.2 (grade 5)
The three tiny bones of the middle ear (the hammer, anvil and stirrup) that carry vibrations from the eardrum to the inner ear.
Grade 5 Life Science: The Human Body, Lesson 7.2 (grade 5)
outcropEnglish
A place where bare rock shows at the surface, such as a cliff, a riverbank or a road cut.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.4 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.3 (grade 3) · Grade 6 Earth Science: The Dynamic Earth, Lesson 9.4 (grade 6) · +3 more
A place where bare rock shows at the surface, such as a cliff, a riverbank or a road cut.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.4 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.3 (grade 3) · Grade 6 Earth Science: The Dynamic Earth, Lesson 9.4 (grade 6) · +3 more
outer coreEnglish
The layer of liquid iron and nickel from about 2,900 km to 5,150 km deep.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.2 (grade 6)
The layer of liquid iron and nickel from about 2,900 km to 5,150 km deep.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.2 (grade 6)
out-of-area contactEnglish
A relative or friend in another region whom every family member can call or text to report where they are, because local phone lines are often jammed after a disaster.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.4 (grade 6)
A relative or friend in another region whom every family member can call or text to report where they are, because local phone lines are often jammed after a disaster.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.4 (grade 6)
overburden (spoil)English
The rock and subsoil that lie above an ore body or coal seam and must be removed to reach it. Once it is dug up and piled, it is called spoil.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.4 (grade 8)
The rock and subsoil that lie above an ore body or coal seam and must be removed to reach it. Once it is dug up and piled, it is called spoil.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.4 (grade 8)
overproductionEnglish
The fact that living things produce more offspring than can possibly survive and reproduce, so there is a struggle for food, space and safety.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.2 (grade 8)
The fact that living things produce more offspring than can possibly survive and reproduce, so there is a struggle for food, space and safety.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.2 (grade 8)
overturning stabilityEnglish
A vessel’s ability to right itself after being tilted by wind or waves instead of rolling over (capsizing).
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.2 (grade 7)
A vessel’s ability to right itself after being tilted by wind or waves instead of rolling over (capsizing).
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.2 (grade 7)
overwinteringEnglish
Spending the winter in one place in a resting state, as monarchs do in the fir forests of Mexico.
Grade 6 Life Science: Animal Design and Behavior, Lesson 2.2 (grade 6)
Spending the winter in one place in a resting state, as monarchs do in the fir forests of Mexico.
Grade 6 Life Science: Animal Design and Behavior, Lesson 2.2 (grade 6)
oviraptoridEnglish
A group of beaked, mostly toothless theropods from Mongolia and China, first named Oviraptor, “egg seizer,” in 1924, and later found brooding their own nests.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.2 (grade 7)
A group of beaked, mostly toothless theropods from Mongolia and China, first named Oviraptor, “egg seizer,” in 1924, and later found brooding their own nests.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.2 (grade 7)
oxygenEnglish
The part of the air we need to breathe. High on a mountain the air is thin, so each breath brings in less of it.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.1 (grade 2) · Grade 2 Gardening & Animals, Lesson 5.1 (grade 2) · Grade 3 Gardening & Animals, Lesson 5.2 (grade 3) · +3 more
The part of the air we need to breathe. High on a mountain the air is thin, so each breath brings in less of it.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.1 (grade 2) · Grade 2 Gardening & Animals, Lesson 5.1 (grade 2) · Grade 3 Gardening & Animals, Lesson 5.2 (grade 3) · +3 more
oxygen isotopesEnglish
Two forms of oxygen, oxygen-16 and the heavier oxygen-18. Snow that falls in cold conditions holds a little less oxygen-18, so the ratio swings between summer and winter.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.4 (grade 7)
Two forms of oxygen, oxygen-16 and the heavier oxygen-18. Snow that falls in cold conditions holds a little less oxygen-18, so the ratio swings between summer and winter.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.4 (grade 7)
P
P, F1 and F2 generationsEnglish
The parent generation (P), their offspring (F1, the first filial generation) and the offspring of the F1 plants (F2, the second filial generation).
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.1 (grade 8)
The parent generation (P), their offspring (F1, the first filial generation) and the offspring of the F1 plants (F2, the second filial generation).
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.1 (grade 8)
P waveEnglish
Primary wave: the fastest seismic wave. It pushes and pulls rock in the direction it travels and can pass through solids, liquids and gases.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.1 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 4.3 (grade 6)
Primary wave: the fastest seismic wave. It pushes and pulls rock in the direction it travels and can pass through solids, liquids and gases.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.1 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 4.3 (grade 6)
pace countEnglish
Measuring distance by counting your steps, using your own measured length per double pace.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.3 (grade 8) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 7.1 (grade 8)
Measuring distance by counting your steps, using your own measured length per double pace.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.3 (grade 8) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 7.1 (grade 8)
packet shipEnglish
A ship that carried mail, and often passengers, on a regular schedule between two ports.
Grade 4 Earth Science: Weather and Water, Lesson 7.4 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 7.1 (grade 6) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 3.4 (grade 8)
A ship that carried mail, and often passengers, on a regular schedule between two ports.
Grade 4 Earth Science: Weather and Water, Lesson 7.4 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 7.1 (grade 6) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 3.4 (grade 8)
pāhoehoeEnglish
(pah-HOH-ay-hoh-ay) Hawaiian lava that cools with a smooth or ropy skin.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.4 (grade 2)
(pah-HOH-ay-hoh-ay) Hawaiian lava that cools with a smooth or ropy skin.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.4 (grade 2)
pairEnglish
Two that go together, like two shoes or two sheep.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 3.4 (grade K) · Kindergarten Life Science: God Made the Animals, Lesson 8.1 (grade K)
Two that go together, like two shoes or two sheep.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 3.4 (grade K) · Kindergarten Life Science: God Made the Animals, Lesson 8.1 (grade K)
palagonite tuffEnglish
A hard brownish rock formed when loose volcanic glass is altered and cemented by warm water and steam.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.4 (grade 6)
A hard brownish rock formed when loose volcanic glass is altered and cemented by warm water and steam.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.4 (grade 6)
paleEnglish
Whitish or yellowish, not a strong color. A plant kept in the dark turns pale.
Kindergarten Life Science: God Made the Animals, Lesson 5.3 (grade K)
Whitish or yellowish, not a strong color. A plant kept in the dark turns pale.
Kindergarten Life Science: God Made the Animals, Lesson 5.3 (grade K)
paleontologistEnglish
A scientist who digs up and studies fossils. Say it: pay-lee-on-TOL-uh-jist.
Grade 2 Earth Science: The Earth's Surface, Lesson 7.1 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.1 (grade 3) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 7.2 (grade K) · +3 more
A scientist who digs up and studies fossils. Say it: pay-lee-on-TOL-uh-jist.
Grade 2 Earth Science: The Earth's Surface, Lesson 7.1 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.1 (grade 3) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 7.2 (grade K) · +3 more
PangaeaEnglish
The name Wegener gave the supercontinent, from Greek words meaning “all land.”
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.1 (grade 6)
The name Wegener gave the supercontinent, from Greek words meaning “all land.”
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.1 (grade 6)
panningEnglish
Shaking and swirling gravel and water in a shallow pan so the light sand washes out and heavy gold stays at the bottom.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.3 (grade 3)
Shaking and swirling gravel and water in a shallow pan so the light sand washes out and heavy gold stays at the bottom.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.3 (grade 3)
pantEnglish
To breathe fast with the tongue out. Dogs pant to cool off, because they do not sweat the way we do.
Kindergarten Life Science: God Made the Animals, Lesson 2.1 (grade K)
To breathe fast with the tongue out. Dogs pant to cool off, because they do not sweat the way we do.
Kindergarten Life Science: God Made the Animals, Lesson 2.1 (grade K)
parabronchiEnglish
The many tiny tubes that run through a bird’s lung. Air flows through them in one direction, and oxygen passes into the blood from them.
Grade 7 Life Science: Cells and Microbes, Lesson 7.2 (grade 7)
The many tiny tubes that run through a bird’s lung. Air flows through them in one direction, and oxygen passes into the blood from them.
Grade 7 Life Science: Cells and Microbes, Lesson 7.2 (grade 7)
paraconformityEnglish
A flat, sharp contact between parallel layers with no visible sign of erosion; it is called a gap only because of fossils or assigned ages, not because of anything seen at the contact.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.2 (grade 7)
A flat, sharp contact between parallel layers with no visible sign of erosion; it is called a gap only because of fossils or assigned ages, not because of anything seen at the contact.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.2 (grade 7)
parallaxEnglish
The way a nearby object seems to shift against a faraway background when you look at it from two different places. Closer objects shift more.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.4 (grade 5) · Grade 5 Geography: Explorers, Navigators and Missionaries, Lesson 5.1 (grade 5)
The way a nearby object seems to shift against a faraway background when you look at it from two different places. Closer objects shift more.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.4 (grade 5) · Grade 5 Geography: Explorers, Navigators and Missionaries, Lesson 5.1 (grade 5)
paralyzeEnglish
To make an animal unable to move while it is still alive.
Grade 6 Life Science: Animal Design and Behavior, Lesson 5.1 (grade 6)
To make an animal unable to move while it is still alive.
Grade 6 Life Science: Animal Design and Behavior, Lesson 5.1 (grade 6)
parent isotopeEnglish
The unstable isotope that decays, such as uranium-238 or carbon-14.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.1 (grade 7)
The unstable isotope that decays, such as uranium-238 or carbon-14.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.1 (grade 7)
parent materialEnglish
The rock or loose sediment from which a soil formed, such as weathered granite, river silt, glacial till or volcanic ash.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.2 (grade 8) · Grade 4 Gardening & Animals, Lesson 3.1 (grade 4) · Grade 7 Gardening & Animals, Lesson 3.1 (grade 7)
The rock or loose sediment from which a soil formed, such as weathered granite, river silt, glacial till or volcanic ash.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.2 (grade 8) · Grade 4 Gardening & Animals, Lesson 3.1 (grade 4) · Grade 7 Gardening & Animals, Lesson 3.1 (grade 7)
parent material (C horizon)English
The loose, partly weathered rock or sediment from which the soil above it formed.
Grade 6 Earth Science: The Dynamic Earth, Lesson 9.2 (grade 6)
The loose, partly weathered rock or sediment from which the soil above it formed.
Grade 6 Earth Science: The Dynamic Earth, Lesson 9.2 (grade 6)
parent plantEnglish
The plant that grew a seed.
Grade 3 Life Science: Plants and Animals Together, Lesson 2.2 (grade 3)
The plant that grew a seed.
Grade 3 Life Science: Plants and Animals Together, Lesson 2.2 (grade 3)
parent rockEnglish
The rock that a metamorphic rock was before it changed. Shale is the parent rock of slate.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.1 (grade 3) · High School Geology, Lesson 1.4 (grade 9–12)
The rock that a metamorphic rock was before it changed. Shale is the parent rock of slate.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.1 (grade 3) · High School Geology, Lesson 1.4 (grade 9–12)
paschal full moonEnglish
The first full moon on or after the church’s spring equinox date, March 21. Easter is the Sunday after it. Paschal comes from Pascha, the Greek and Latin word for Passover.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.4 (grade 5)
The first full moon on or after the church’s spring equinox date, March 21. Easter is the Sunday after it. Paschal comes from Pascha, the Greek and Latin word for Passover.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.4 (grade 5)
passive sonarEnglish
Sonar that only listens for sounds other things make, such as a ship’s engine or a whale’s song, without sending a ping.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.3 (grade 6)
Sonar that only listens for sounds other things make, such as a ship’s engine or a whale’s song, without sending a ping.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.3 (grade 6)
PassoverEnglish
The feast God gave Israel in Exodus 12 to remember their rescue from Egypt. The Passover lamb was killed on the evening of the fourteenth day of the first month, in spring.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.4 (grade 5)
The feast God gave Israel in Exodus 12 to remember their rescue from Egypt. The Passover lamb was killed on the evening of the fourteenth day of the first month, in spring.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.4 (grade 5)
patinaEnglish
A thin coat that forms on the outside of a metal over time. Copper grows a green patina that protects the metal underneath.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.2 (grade 3)
A thin coat that forms on the outside of a metal over time. Copper grows a green patina that protects the metal underneath.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.2 (grade 3)
peatEnglish
A soft, brown, spongy mass of partly decayed plants that has been soaked in water. Buried and squeezed, it can become coal.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.3 (grade 3) · Grade 7 Earth Science: Earth History and the Flood, Lesson 2.4 (grade 7)
A soft, brown, spongy mass of partly decayed plants that has been soaked in water. Buried and squeezed, it can become coal.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.3 (grade 3) · Grade 7 Earth Science: Earth History and the Flood, Lesson 2.4 (grade 7)
pebbleEnglish
A small rock that fits in your hand, from about the size of a pea up to a tennis ball.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 1.3 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 9.4 (grade 2) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.1 (grade K) · +1 more
A small rock that fits in your hand, from about the size of a pea up to a tennis ball.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 1.3 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 9.4 (grade 2) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.1 (grade K) · +1 more
pegEnglish
The stalk that grows down from a peanut flower after it blooms and pushes into the soil, where the peanut pod forms.
Grade 3 Life Science: Plants and Animals Together, Lesson 1.4 (grade 3) · Threads & Weaving, Lesson 6.3 (grade 9–12)
The stalk that grows down from a peanut flower after it blooms and pushes into the soil, where the peanut pod forms.
Grade 3 Life Science: Plants and Animals Together, Lesson 1.4 (grade 3) · Threads & Weaving, Lesson 6.3 (grade 9–12)
pendulumEnglish
A weight hanging from a string or rod that swings back and forth under the pull of gravity.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.4 (grade 5) · Grade 2 Engineering & Physics, Lesson 9.3 (grade 2) · Grade 3 Engineering & Physics, Lesson 9.2 (grade 3) · +2 more
A weight hanging from a string or rod that swings back and forth under the pull of gravity.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.4 (grade 5) · Grade 2 Engineering & Physics, Lesson 9.3 (grade 2) · Grade 3 Engineering & Physics, Lesson 9.2 (grade 3) · +2 more
penguinEnglish
A bird with feathers and a beak that cannot fly but swims very fast in the sea.
Grade 1 Life Science: Animal Homes and Habits, Lesson 5.2 (grade 1)
A bird with feathers and a beak that cannot fly but swims very fast in the sea.
Grade 1 Life Science: Animal Homes and Habits, Lesson 5.2 (grade 1)
penicillinEnglish
The first widely used antibiotic, made by the mold Penicillium. It stops bacteria from building their cell walls.
Grade 7 Life Science: Cells and Microbes, Lesson 4.3 (grade 7)
The first widely used antibiotic, made by the mold Penicillium. It stops bacteria from building their cell walls.
Grade 7 Life Science: Cells and Microbes, Lesson 4.3 (grade 7)
PenicilliumEnglish
A common blue-green mold, a kind of fungus, that grows on bread, fruit and damp places.
Grade 7 Life Science: Cells and Microbes, Lesson 4.3 (grade 7)
A common blue-green mold, a kind of fungus, that grows on bread, fruit and damp places.
Grade 7 Life Science: Cells and Microbes, Lesson 4.3 (grade 7)
pennaceous featherEnglish
A feather with a stiff rachis and a closed, flat vane, such as a flight feather or body contour feather.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.4 (grade 7) · Explore Dinosaurs · Expert, Stop 3.7 (Ages 14+)
A feather with a stiff rachis and a closed, flat vane, such as a flight feather or body contour feather.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.4 (grade 7) · Explore Dinosaurs · Expert, Stop 3.7 (Ages 14+)
penumbraEnglish
The lighter outer part of a shadow, where only part of the light is blocked. Inside the Moon’s penumbra you see a partial eclipse.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.3 (grade 5)
The lighter outer part of a shadow, where only part of the light is blocked. Inside the Moon’s penumbra you see a partial eclipse.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.3 (grade 5)
percent modern carbon (pMC)English
A sample’s carbon-14 level compared with a living thing today. Living wood is 100 pMC; a sample with half as much is 50 pMC.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.3 (grade 7)
A sample’s carbon-14 level compared with a living thing today. Living wood is 100 pMC; a sample with half as much is 50 pMC.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.3 (grade 7)
perching footEnglish
A foot with three toes pointing forward and one pointing back, made for gripping a branch.
Grade 4 Life Science: Classification, Lesson 4.2 (grade 4)
A foot with three toes pointing forward and one pointing back, made for gripping a branch.
Grade 4 Life Science: Classification, Lesson 4.2 (grade 4)
peristalsisEnglish
Waves of muscle squeezing that push food along the digestive tract, the way you pushed the ball through the sock.
Grade 5 Life Science: The Human Body, Lesson 5.3 (grade 5)
Waves of muscle squeezing that push food along the digestive tract, the way you pushed the ball through the sock.
Grade 5 Life Science: The Human Body, Lesson 5.3 (grade 5)
permafrostEnglish
Ground that stays frozen all year, found across Siberia, Alaska and northern Canada; it can preserve flesh, hair and plants for a very long time.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.2 (grade 7) · Explore Dinosaurs · Expert, Stop 5.6 (Ages 14+) · Explore Dinosaurs · Ranger, Stop 5.6 (Ages 10–13) · +3 more
Ground that stays frozen all year, found across Siberia, Alaska and northern Canada; it can preserve flesh, hair and plants for a very long time.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.2 (grade 7) · Explore Dinosaurs · Expert, Stop 5.6 (Ages 14+) · Explore Dinosaurs · Ranger, Stop 5.6 (Ages 10–13) · +3 more
permeabilityEnglish
How easily water can move through a material, which depends on whether the pores are large and connected.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.2 (grade 8) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.3 (grade 8) · High School Geology, Lesson 4.1 (grade 9–12)
How easily water can move through a material, which depends on whether the pores are large and connected.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.2 (grade 8) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.3 (grade 8) · High School Geology, Lesson 4.1 (grade 9–12)
permeableEnglish
Letting water pass through easily. Gravel and sand are permeable; clay lets water through only very slowly.
Grade 4 Earth Science: Weather and Water, Lesson 1.4 (grade 4)
Letting water pass through easily. Gravel and sand are permeable; clay lets water through only very slowly.
Grade 4 Earth Science: Weather and Water, Lesson 1.4 (grade 4)
permineralizationEnglish
Preservation in which mineral-bearing water fills the pores of bone, shell, or wood and deposits minerals there, turning the original into stone while keeping its structure.
High School Geology, Lesson 5.1 (grade 9–12)
Preservation in which mineral-bearing water fills the pores of bone, shell, or wood and deposits minerals there, turning the original into stone while keeping its structure.
High School Geology, Lesson 5.1 (grade 9–12)
persistence forecastEnglish
The simplest forecast: “tomorrow will be like today.” A good forecaster tries to do better than it.
Grade 4 Earth Science: Weather and Water, Lesson 5.4 (grade 4) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.4 (grade 8)
The simplest forecast: “tomorrow will be like today.” A good forecaster tries to do better than it.
Grade 4 Earth Science: Weather and Water, Lesson 5.4 (grade 4) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.4 (grade 8)
petrifiedEnglish
Turned to stone: minerals carried by water have filled and replaced the bone, shell or wood.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.1 (grade 3)
Turned to stone: minerals carried by water have filled and replaced the bone, shell or wood.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.1 (grade 3)
petroleumEnglish
Natural crude oil, a dark liquid mixture of hydrocarbons found in the pore spaces of rock. From Latin petra (rock) and oleum (oil).
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.1 (grade 8) · Grade 7 Geography: Regions of the World, Lesson 3.4 (grade 7)
Natural crude oil, a dark liquid mixture of hydrocarbons found in the pore spaces of rock. From Latin petra (rock) and oleum (oil).
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.1 (grade 8) · Grade 7 Geography: Regions of the World, Lesson 3.4 (grade 7)
phagocyteEnglish
A white blood cell that surrounds and swallows germs and debris. The name means “eating cell.”
Grade 7 Life Science: Cells and Microbes, Lesson 4.4 (grade 7)
A white blood cell that surrounds and swallows germs and debris. The name means “eating cell.”
Grade 7 Life Science: Cells and Microbes, Lesson 4.4 (grade 7)
phaseEnglish
The shape of the lit part of the Moon as we see it from Earth on a certain night.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.2 (grade 5)
The shape of the lit part of the Moon as we see it from Earth on a certain night.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.2 (grade 5)
phenocrystEnglish
A large crystal in a volcanic rock that grew in the magma before the eruption, often earlier than the fine-grained groundmass around it.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.4 (grade 7)
A large crystal in a volcanic rock that grew in the magma before the eruption, often earlier than the fine-grained groundmass around it.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.4 (grade 7)
phenotypeEnglish
The trait you can actually observe, such as a round seed or a wrinkled seed.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.2 (grade 8)
The trait you can actually observe, such as a round seed or a wrinkled seed.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.2 (grade 8)
PhilippiEnglish
A city in Macedonia, in the north of Greece today, where Paul started a church. You can still visit its ruins.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.4 (grade 2) · Explore Hospitality and Home · Expert, Stop 4.7 (Ages 14+) · Explore Hospitality and Home · Ranger, Stop 4.7 (Ages 10–13) · +1 more
A city in Macedonia, in the north of Greece today, where Paul started a church. You can still visit its ruins.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.4 (grade 2) · Explore Hospitality and Home · Expert, Stop 4.7 (Ages 14+) · Explore Hospitality and Home · Ranger, Stop 4.7 (Ages 10–13) · +1 more
phonic lipsEnglish
Pairs of fatty lips in a dolphin’s nasal passage, just below the blowhole, that snap together to make clicks.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.2 (grade 6)
Pairs of fatty lips in a dolphin’s nasal passage, just below the blowhole, that snap together to make clicks.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.2 (grade 6)
phonoliteEnglish
A gray-green igneous rock with small crystals. Devils Tower is made of phonolite.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.4 (grade 3)
A gray-green igneous rock with small crystals. Devils Tower is made of phonolite.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.4 (grade 3)
phylumEnglish
A large group of animals that share one basic body plan, such as arthropods (jointed legs and an outer skeleton), mollusks or chordates. The plural is phyla.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.1 (grade 8)
A large group of animals that share one basic body plan, such as arthropods (jointed legs and an outer skeleton), mollusks or chordates. The plural is phyla.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.1 (grade 8)
physical constantEnglish
A number in the laws of nature that does not change, such as the strength of gravity or the charge of an electron.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.4 (grade 8)
A number in the laws of nature that does not change, such as the strength of gravity or the charge of an electron.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.4 (grade 8)
physiologyEnglish
The study of how the parts of a living body work and work together, such as how the heart pumps blood.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.1 (grade 8)
The study of how the parts of a living body work and work together, such as how the heart pumps blood.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.1 (grade 8)
picture chartEnglish
A chart that uses little pictures or dots to show how many of each thing there are.
Grade 1 Life Science: Animal Homes and Habits, Lesson 9.2 (grade 1)
A chart that uses little pictures or dots to show how many of each thing there are.
Grade 1 Life Science: Animal Homes and Habits, Lesson 9.2 (grade 1)
pinwheelEnglish
A toy wheel with paper blades that spins when the wind pushes it.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.2 (grade K) · Kindergarten Engineering & Physics, Lesson 9.3 (grade K)
A toy wheel with paper blades that spins when the wind pushes it.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.2 (grade K) · Kindergarten Engineering & Physics, Lesson 9.3 (grade K)
pitfall trapEnglish
A cup set into the ground with its rim level with the soil, so small crawling animals tumble in and can be counted and let go.
Grade 3 Life Science: Plants and Animals Together, Lesson 9.2 (grade 3)
A cup set into the ground with its rim level with the soil, so small crawling animals tumble in and can be counted and let go.
Grade 3 Life Science: Plants and Animals Together, Lesson 9.2 (grade 3)
placental mammalEnglish
A mammal whose baby grows much longer inside its mother before birth. Dogs, mice, bison and most other mammals are placental mammals.
Grade 4 Life Science: Classification, Lesson 5.2 (grade 4)
A mammal whose baby grows much longer inside its mother before birth. Dogs, mice, bison and most other mammals are placental mammals.
Grade 4 Life Science: Classification, Lesson 5.2 (grade 4)
placerEnglish
A deposit of heavy minerals such as gold or tin sorted and concentrated by running water.
High School Geology, Lesson 7.1 (grade 9–12)
A deposit of heavy minerals such as gold or tin sorted and concentrated by running water.
High School Geology, Lesson 7.1 (grade 9–12)
placer depositEnglish
Grains and nuggets of a heavy mineral that have weathered out of the rock and been concentrated by moving water in stream gravels.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.1 (grade 8)
Grains and nuggets of a heavy mineral that have weathered out of the rock and been concentrated by moving water in stream gravels.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.1 (grade 8)
placer goldEnglish
Gold found loose in sand and gravel, washed out of rocks by water (say PLASS-er).
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.3 (grade 3)
Gold found loose in sand and gravel, washed out of rocks by water (say PLASS-er).
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.3 (grade 3)
planetEnglish
A large, round world that travels around the Sun and shines by reflecting sunlight. The word comes from the Greek word for “wanderer.”
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.1 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.4 (grade 5) · Grade 3 Greek, Lesson 1.2 (grade 3) · +1 more
A large, round world that travels around the Sun and shines by reflecting sunlight. The word comes from the Greek word for “wanderer.”
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.1 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.4 (grade 5) · Grade 3 Greek, Lesson 1.2 (grade 3) · +1 more
plant breedingEnglish
Crossing chosen parent plants and selecting the best offspring, generation after generation, to develop better varieties.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.3 (grade 8)
Crossing chosen parent plants and selecting the best offspring, generation after generation, to develop better varieties.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.3 (grade 8)
plant eaterEnglish
An animal that eats leaves, stems, seeds or fruit. Scientists call it an herbivore.
Grade 2 Earth Science: The Earth's Surface, Lesson 7.3 (grade 2)
An animal that eats leaves, stems, seeds or fruit. Scientists call it an herbivore.
Grade 2 Earth Science: The Earth's Surface, Lesson 7.3 (grade 2)
plant pressEnglish
A stack of paper squeezed flat under weight, used to dry leaves and flowers so they keep their shape.
Grade 3 Life Science: Plants and Animals Together, Lesson 9.4 (grade 3) · Grade 4 Life Science: Classification, Lesson 6.4 (grade 4)
A stack of paper squeezed flat under weight, used to dry leaves and flowers so they keep their shape.
Grade 3 Life Science: Plants and Animals Together, Lesson 9.4 (grade 3) · Grade 4 Life Science: Classification, Lesson 6.4 (grade 4)
plant-eaterEnglish
An animal that eats leaves, grass, seeds or other plants, not other animals.
Grade 1 Life Science: Animal Homes and Habits, Lesson 7.2 (grade 1) · Kindergarten Life Science: God Made the Animals, Lesson 7.2 (grade K)
An animal that eats leaves, grass, seeds or other plants, not other animals.
Grade 1 Life Science: Animal Homes and Habits, Lesson 7.2 (grade 1) · Kindergarten Life Science: God Made the Animals, Lesson 7.2 (grade K)
plasmidEnglish
A small ring of DNA, separate from the main chromosome, that bacteria can copy and pass to other bacteria. Many resistance genes travel on plasmids.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.3 (grade 8)
A small ring of DNA, separate from the main chromosome, that bacteria can copy and pass to other bacteria. Many resistance genes travel on plasmids.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.3 (grade 8)
plaster jacketEnglish
A hard shell of cloth soaked in wet plaster, wrapped around a fossil and the rock around it to protect it on the trip to the museum.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.2 (grade 3)
A hard shell of cloth soaked in wet plaster, wrapped around a fossil and the rock around it to protect it on the trip to the museum.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.2 (grade 3)
plateauEnglish
A high, broad, fairly flat region. The Tibetan Plateau north of the Himalaya averages more than 4,500 m above sea level.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.3 (grade 6) · Grade 1 Geography: Maps and Journeys, Lesson 3.1 (grade 1) · Grade 1 Geography: Maps and Journeys, Lesson 7.2 (grade 1) · +3 more
A high, broad, fairly flat region. The Tibetan Plateau north of the Himalaya averages more than 4,500 m above sea level.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.3 (grade 6) · Grade 1 Geography: Maps and Journeys, Lesson 3.1 (grade 1) · Grade 1 Geography: Maps and Journeys, Lesson 7.2 (grade 1) · +3 more
plateletEnglish
A tiny piece of a cell that helps blood clot. Platelets stick together to plug a cut and start a scab.
Grade 5 Life Science: The Human Body, Lesson 3.3 (grade 5)
A tiny piece of a cell that helps blood clot. Platelets stick together to plug a cut and start a scab.
Grade 5 Life Science: The Human Body, Lesson 3.3 (grade 5)
platypusEnglish
A furry mammal from Australia with a flat bill, webbed feet and a wide tail. The mother lays eggs and feeds her babies milk.
Grade 2 Life Science: Animal Families, Lesson 1.4 (grade 2)
A furry mammal from Australia with a flat bill, webbed feet and a wide tail. The mother lays eggs and feeds her babies milk.
Grade 2 Life Science: Animal Families, Lesson 1.4 (grade 2)
playback experimentEnglish
An experiment in which scientists play recorded animal sounds through a loudspeaker and watch how wild animals respond.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.3 (grade 6)
An experiment in which scientists play recorded animal sounds through a loudspeaker and watch how wild animals respond.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.3 (grade 6)
PleiadesEnglish
A small, tight cluster of bright blue-white stars in Taurus, also called the Seven Sisters. In the Hebrew of Job it is called Kimah.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.2 (grade 5)
A small, tight cluster of bright blue-white stars in Taurus, also called the Seven Sisters. In the Hebrew of Job it is called Kimah.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.2 (grade 5)
Plinian eruptionEnglish
A very explosive eruption with a tall, steady column that rains pumice over a wide area, named after Pliny the Younger, who described the first one on record.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.1 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 3.1 (grade 6)
A very explosive eruption with a tall, steady column that rains pumice over a wide area, named after Pliny the Younger, who described the first one on record.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.1 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 3.1 (grade 6)
pluckingEnglish
Erosion in which fast water pries whole blocks of rock loose along cracks and carries them away. It is the main way floods cut bedrock canyons quickly.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.4 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 4.4 (grade 6)
Erosion in which fast water pries whole blocks of rock loose along cracks and carries them away. It is the main way floods cut bedrock canyons quickly.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.4 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 4.4 (grade 6)
plunge poolEnglish
The deep basin at the foot of a waterfall, drilled by the falling water and the stones it churns.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.1 (grade 6)
The deep basin at the foot of a waterfall, drilled by the falling water and the stones it churns.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.1 (grade 6)
pluvial lakeEnglish
A large lake, such as Lake Bonneville, that filled a dry basin during a wetter, cooler period.
High School Geology, Lesson 6.4 (grade 9–12)
A large lake, such as Lake Bonneville, that filled a dry basin during a wetter, cooler period.
High School Geology, Lesson 6.4 (grade 9–12)
pneumatic bonesEnglish
Hollow bones filled with air and connected to the air sacs, such as the upper wing bone (humerus) in many birds.
Grade 7 Life Science: Cells and Microbes, Lesson 7.2 (grade 7)
Hollow bones filled with air and connected to the air sacs, such as the upper wing bone (humerus) in many birds.
Grade 7 Life Science: Cells and Microbes, Lesson 7.2 (grade 7)
point barEnglish
The crescent of sand and gravel that builds on the inside of a creek bend, where the water runs slowest.
Grade 7 Earth Science: Earth History and the Flood, Lesson 9.3 (grade 7) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 9.4 (grade 6)
The crescent of sand and gravel that builds on the inside of a creek bend, where the water runs slowest.
Grade 7 Earth Science: Earth History and the Flood, Lesson 9.3 (grade 7) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 9.4 (grade 6)
pointer starsEnglish
The two stars at the end of the Big Dipper’s bowl, Merak and Dubhe. A line through them points to Polaris.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.1 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.2 (grade 5)
The two stars at the end of the Big Dipper’s bowl, Merak and Dubhe. A line through them points to Polaris.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.1 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.2 (grade 5)
polar zoneEnglish
The cold zone beyond the Arctic Circle or the Antarctic Circle (about 66.5° N and S), where the sun stays low in the sky and winters are long and dark.
Grade 4 Earth Science: Weather and Water, Lesson 8.1 (grade 4)
The cold zone beyond the Arctic Circle or the Antarctic Circle (about 66.5° N and S), where the sun stays low in the sky and winters are long and dark.
Grade 4 Earth Science: Weather and Water, Lesson 8.1 (grade 4)
PolarisEnglish
The North Star: a star that sits almost exactly above the earth’s North Pole, so it stays nearly still in the sky all night and all year.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.1 (grade 5)
The North Star: a star that sits almost exactly above the earth’s North Pole, so it stays nearly still in the sky all night and all year.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.1 (grade 5)
poleEnglish
One of the two ends of the earth, the farthest north or the farthest south.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.4 (grade 2) · Grade 1 Engineering & Physics, Lesson 4.3 (grade 1) · Grade 3 Engineering & Physics, Lesson 4.3 (grade 3) · +2 more
One of the two ends of the earth, the farthest north or the farthest south.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.4 (grade 2) · Grade 1 Engineering & Physics, Lesson 4.3 (grade 1) · Grade 3 Engineering & Physics, Lesson 4.3 (grade 3) · +2 more
pollen basketEnglish
A smooth hollow ringed with stiff hairs on each back leg of a honey bee, where it packs pollen to carry home.
Grade 3 Life Science: Plants and Animals Together, Lesson 3.1 (grade 3)
A smooth hollow ringed with stiff hairs on each back leg of a honey bee, where it packs pollen to carry home.
Grade 3 Life Science: Plants and Animals Together, Lesson 3.1 (grade 3)
polyploidEnglish
Having more than two full sets of chromosomes. Garden strawberries have eight sets.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.2 (grade 8)
Having more than two full sets of chromosomes. Garden strawberries have eight sets.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.2 (grade 8)
polystrate fossilEnglish
A fossil, often an upright tree trunk, that passes through two or more rock layers. “Poly” means many and “strate” means layers.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.4 (grade 3) · Grade 7 Earth Science: Earth History and the Flood, Lesson 2.4 (grade 7) · High School Geology, Lesson 6.2 (grade 9–12)
A fossil, often an upright tree trunk, that passes through two or more rock layers. “Poly” means many and “strate” means layers.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.4 (grade 3) · Grade 7 Earth Science: Earth History and the Flood, Lesson 2.4 (grade 7) · High School Geology, Lesson 6.2 (grade 9–12)
population bottleneckEnglish
A sharp drop in a population to very few individuals. Afterward, all the survivors’ descendants carry only the gene variety those few survivors had.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 7.3 (grade 8)
A sharp drop in a population to very few individuals. Afterward, all the survivors’ descendants carry only the gene variety those few survivors had.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 7.3 (grade 8)
poresEnglish
Tiny holes on the underside of some mushrooms, such as boletes, that open from tubes where spores are made instead of gills.
Grade 7 Life Science: Cells and Microbes, Lesson 6.3 (grade 7)
Tiny holes on the underside of some mushrooms, such as boletes, that open from tubes where spores are made instead of gills.
Grade 7 Life Science: Cells and Microbes, Lesson 6.3 (grade 7)
porosityEnglish
The fraction of a material’s volume that is empty space (pores), usually given as a percent. Water can be stored only in the pores.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.2 (grade 8) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.3 (grade 8) · Grade 7 Gardening & Animals, Lesson 3.2 (grade 7)
The fraction of a material’s volume that is empty space (pores), usually given as a percent. Water can be stored only in the pores.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.2 (grade 8) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.3 (grade 8) · Grade 7 Gardening & Animals, Lesson 3.2 (grade 7)
potassium-argon datingEnglish
A method that measures potassium-40 and its daughter argon-40 in a rock and calculates an age using the 1.25 billion year half-life, assuming the argon count started at zero when the lava hardened.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.4 (grade 7)
A method that measures potassium-40 and its daughter argon-40 in a rock and calculates an age using the 1.25 billion year half-life, assuming the argon count started at zero when the lava hardened.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.4 (grade 7)
precipitateEnglish
To come out of a liquid as a solid that can be seen. DNA precipitates in cold alcohol because it does not dissolve there.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.2 (grade 8)
To come out of a liquid as a solid that can be seen. DNA precipitates in cold alcohol because it does not dissolve there.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.2 (grade 8)
precipitationEnglish
Water falling from clouds to the ground as rain, snow, sleet or hail.
Grade 4 Earth Science: Weather and Water, Lesson 1.1 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 8.4 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 9.1 (grade 4) · +2 more
Water falling from clouds to the ground as rain, snow, sleet or hail.
Grade 4 Earth Science: Weather and Water, Lesson 1.1 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 8.4 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 9.1 (grade 4) · +2 more
predatorEnglish
An animal that hunts and eats other animals.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.3 (grade 3) · Explore Animals · Ranger, Stop 1.1 (Ages 10–13) · Explore Animals, Stop 4.1 (Ages 7–9) · +3 more
An animal that hunts and eats other animals.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.3 (grade 3) · Explore Animals · Ranger, Stop 1.1 (Ages 10–13) · Explore Animals, Stop 4.1 (Ages 7–9) · +3 more
predator and preyEnglish
A predator is an animal that hunts and eats other animals; the animals it eats are its prey. Wolves are predators; moose, elk and deer are among their prey.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.2 (grade 6)
A predator is an animal that hunts and eats other animals; the animals it eats are its prey. Wolves are predators; moose, elk and deer are among their prey.
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.2 (grade 6)
preenEnglish
To clean and smooth the feathers with the bill. A duck spreads a little oil from near its tail over its feathers when it preens.
Grade 1 Life Science: Animal Homes and Habits, Lesson 2.2 (grade 1)
To clean and smooth the feathers with the bill. A duck spreads a little oil from near its tail over its feathers when it preens.
Grade 1 Life Science: Animal Homes and Habits, Lesson 2.2 (grade 1)
preparatorEnglish
A museum worker who carefully cleans rock away from fossil bones and repairs them.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.3 (grade 3) · Explore Dinosaurs · Expert, Stop 2.7 (Ages 14+) · Explore Dinosaurs · Ranger, Stop 2.9 (Ages 10–13)
A museum worker who carefully cleans rock away from fossil bones and repairs them.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.3 (grade 3) · Explore Dinosaurs · Expert, Stop 2.7 (Ages 14+) · Explore Dinosaurs · Ranger, Stop 2.9 (Ages 10–13)
prepared slideEnglish
A permanent slide, usually of a very thin, stained slice of tissue sealed under a coverslip, made to last for years.
Grade 7 Life Science: Cells and Microbes, Lesson 1.3 (grade 7)
A permanent slide, usually of a very thin, stained slice of tissue sealed under a coverslip, made to last for years.
Grade 7 Life Science: Cells and Microbes, Lesson 1.3 (grade 7)
preservedEnglish
Kept safe from rotting or breaking apart, so that its shape lasts.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.3 (grade 3)
Kept safe from rotting or breaking apart, so that its shape lasts.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.3 (grade 3)
pressure waveEnglish
A ripple of squeezed and stretched air that travels outward from an explosion at about the speed of sound.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.2 (grade 6) · Grade 6 Life Science: Animal Design and Behavior, Lesson 8.4 (grade 6)
A ripple of squeezed and stretched air that travels outward from an explosion at about the speed of sound.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.2 (grade 6) · Grade 6 Life Science: Animal Design and Behavior, Lesson 8.4 (grade 6)
prevailEnglish
The word Genesis uses for the waters rising and holding power over the land. The waters “prevailed upon the earth an hundred and fifty days” (Genesis 7:24).
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.4 (grade 6)
The word Genesis uses for the waters rising and holding power over the land. The waters “prevailed upon the earth an hundred and fifty days” (Genesis 7:24).
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.4 (grade 6)
prevailing westerliesEnglish
The winds that usually blow from west to east across the middle latitudes, carrying weather systems with them.
Grade 4 Earth Science: Weather and Water, Lesson 5.1 (grade 4) · Technology Overcoming Geography, Lesson 4.3 (grade 9–12)
The winds that usually blow from west to east across the middle latitudes, carrying weather systems with them.
Grade 4 Earth Science: Weather and Water, Lesson 5.1 (grade 4) · Technology Overcoming Geography, Lesson 4.3 (grade 9–12)
preyEnglish
An animal that is hunted and eaten by another animal.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.3 (grade 3) · Explore Animals, Stop 2.2 (Ages 7–9) · Explore Animals, Stop 6.2 (Ages 7–9) · +3 more
An animal that is hunted and eaten by another animal.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.3 (grade 3) · Explore Animals, Stop 2.2 (Ages 7–9) · Explore Animals, Stop 6.2 (Ages 7–9) · +3 more
primateEnglish
A mammal with grasping hands, forward-facing eyes, nails on most fingers and toes, and a large brain for its size. Lemurs, monkeys and apes are primates.
Grade 4 Life Science: Classification, Lesson 5.3 (grade 4)
A mammal with grasping hands, forward-facing eyes, nails on most fingers and toes, and a large brain for its size. Lemurs, monkeys and apes are primates.
Grade 4 Life Science: Classification, Lesson 5.3 (grade 4)
prime meridianEnglish
The meridian at 0° longitude, which runs through Greenwich, England. It was chosen as the world’s starting line in 1884.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.4 (grade 5) · Explore Travel and Faraway Places · Expert, Stop 1.3 (Ages 14+) · Explore Travel and Faraway Places · Expert, Stop 3.7 (Ages 14+) · +3 more
The meridian at 0° longitude, which runs through Greenwich, England. It was chosen as the world’s starting line in 1884.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.4 (grade 5) · Explore Travel and Faraway Places · Expert, Stop 1.3 (Ages 14+) · Explore Travel and Faraway Places · Expert, Stop 3.7 (Ages 14+) · +3 more
principleEnglish
The rule that makes a design work, such as “many hooks catch many loops.” Biomimicry copies principles, not just shapes.
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.4 (grade 6)
The rule that makes a design work, such as “many hooks catch many loops.” Biomimicry copies principles, not just shapes.
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.4 (grade 6)
principle of faunal successionEnglish
The observation that each rock layer in a sequence contains its own set of fossils, in the same order wherever the layers are found, so fossils can be used to identify a layer.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.1 (grade 8)
The observation that each rock layer in a sequence contains its own set of fossils, in the same order wherever the layers are found, so fossils can be used to identify a layer.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.1 (grade 8)
prismEnglish
A clear wedge of glass or plastic that bends light and spreads it out into its colors.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.3 (grade 5) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.3 (grade K) · Geometry, Lesson 12.1 (grade 9–10) · +2 more
A clear wedge of glass or plastic that bends light and spreads it out into its colors.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.3 (grade 5) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.3 (grade K) · Geometry, Lesson 12.1 (grade 9–10) · +2 more
prokaryoteEnglish
A cell without a nucleus or other membrane-wrapped organelles. Bacteria (and the similar-looking archaea) are prokaryotes. Cells with a nucleus, like yours, are eukaryotes.
Grade 7 Life Science: Cells and Microbes, Lesson 3.1 (grade 7)
A cell without a nucleus or other membrane-wrapped organelles. Bacteria (and the similar-looking archaea) are prokaryotes. Cells with a nucleus, like yours, are eukaryotes.
Grade 7 Life Science: Cells and Microbes, Lesson 3.1 (grade 7)
prosimianEnglish
A small primate such as a lemur, loris or galago, often with big eyes for seeing at night and a wet nose like a dog’s.
Grade 4 Life Science: Classification, Lesson 5.3 (grade 4)
A small primate such as a lemur, loris or galago, often with big eyes for seeing at night and a wet nose like a dog’s.
Grade 4 Life Science: Classification, Lesson 5.3 (grade 4)
protistEnglish
A single-celled (or simple many-celled) living thing with a nucleus that is not a plant, animal or fungus. Paramecium, amoeba and euglena are protists.
Grade 7 Life Science: Cells and Microbes, Lesson 1.4 (grade 7) · Grade 7 Life Science: Cells and Microbes, Lesson 3.2 (grade 7)
A single-celled (or simple many-celled) living thing with a nucleus that is not a plant, animal or fungus. Paramecium, amoeba and euglena are protists.
Grade 7 Life Science: Cells and Microbes, Lesson 1.4 (grade 7) · Grade 7 Life Science: Cells and Microbes, Lesson 3.2 (grade 7)
protozoaEnglish
Animal-like protists that take in food, such as amoebas and paramecia. The word means “first animals,” though they are not animals.
Grade 7 Life Science: Cells and Microbes, Lesson 3.2 (grade 7)
Animal-like protists that take in food, such as amoebas and paramecia. The word means “first animals,” though they are not animals.
Grade 7 Life Science: Cells and Microbes, Lesson 3.2 (grade 7)
pseudopodEnglish
“False foot”: a bulge of cytoplasm that an amoeba pushes out to creep along and to surround its food.
Grade 7 Life Science: Cells and Microbes, Lesson 1.4 (grade 7) · Grade 7 Life Science: Cells and Microbes, Lesson 3.2 (grade 7)
“False foot”: a bulge of cytoplasm that an amoeba pushes out to creep along and to surround its food.
Grade 7 Life Science: Cells and Microbes, Lesson 1.4 (grade 7) · Grade 7 Life Science: Cells and Microbes, Lesson 3.2 (grade 7)
pubisEnglish
One of the three bones on each side of the hip. It points forward in lizard-hipped dinosaurs and backward in bird-hipped dinosaurs.
Grade 4 Life Science: Classification, Lesson 7.4 (grade 4)
One of the three bones on each side of the hip. It points forward in lizard-hipped dinosaurs and backward in bird-hipped dinosaurs.
Grade 4 Life Science: Classification, Lesson 7.4 (grade 4)
puddleEnglish
A small pool of water that gathers in a low spot after rain.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.2 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 3.2 (grade K) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.2 (grade K) · +1 more
A small pool of water that gathers in a low spot after rain.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.2 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 3.2 (grade K) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.2 (grade K) · +1 more
pumiceEnglish
A light, gray or white lava rock full of tiny holes left by gas bubbles. Most pumice can float on water.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.3 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.3 (grade 3) · Grade 6 Earth Science: The Dynamic Earth, Lesson 3.1 (grade 6) · +3 more
A light, gray or white lava rock full of tiny holes left by gas bubbles. Most pumice can float on water.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.3 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.3 (grade 3) · Grade 6 Earth Science: The Dynamic Earth, Lesson 3.1 (grade 6) · +3 more
punctuated equilibriumEnglish
The 1972 proposal by Niles Eldredge and Stephen Jay Gould that most fossil kinds show stasis, with change happening in short bursts too brief to leave many fossils.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.4 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.4 (grade 8)
The 1972 proposal by Niles Eldredge and Stephen Jay Gould that most fossil kinds show stasis, with change happening in short bursts too brief to leave many fossils.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.4 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.4 (grade 8)
pupilEnglish
The round black dot in the middle of your eye. It is a little opening that lets light in.
Grade 1 Life Science: Animal Homes and Habits, Lesson 8.1 (grade 1) · Grade 5 Life Science: The Human Body, Lesson 7.1 (grade 5)
The round black dot in the middle of your eye. It is a little opening that lets light in.
Grade 1 Life Science: Animal Homes and Habits, Lesson 8.1 (grade 1) · Grade 5 Life Science: The Human Body, Lesson 7.1 (grade 5)
puppyEnglish
A baby dog. Puppies are born with their eyes shut and drink milk from their mother.
Kindergarten Life Science: God Made the Animals, Lesson 2.1 (grade K)
A baby dog. Puppies are born with their eyes shut and drink milk from their mother.
Kindergarten Life Science: God Made the Animals, Lesson 2.1 (grade K)
purrEnglish
The soft rumbling sound a cat makes, often when it is happy and comfortable.
Kindergarten Life Science: God Made the Animals, Lesson 2.2 (grade K)
The soft rumbling sound a cat makes, often when it is happy and comfortable.
Kindergarten Life Science: God Made the Animals, Lesson 2.2 (grade K)
pyriteEnglish
A brassy, gold-colored mineral called “fool’s gold.” It leaves a greenish-black streak and is hard enough to scratch glass.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.2 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.3 (grade 3)
A brassy, gold-colored mineral called “fool’s gold.” It leaves a greenish-black streak and is hard enough to scratch glass.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.2 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.3 (grade 3)
pyroclastic flowEnglish
A fast, ground-hugging avalanche of hot gas, ash and rock that rushes down a volcano’s sides at more than 100 km per hour.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.1 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 3.1 (grade 6) · High School Geology, Lesson 2.3 (grade 9–12)
A fast, ground-hugging avalanche of hot gas, ash and rock that rushes down a volcano’s sides at more than 100 km per hour.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.1 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 3.1 (grade 6) · High School Geology, Lesson 2.3 (grade 9–12)
Q
quadrangleEnglish
A rectangular map area bounded by lines of latitude and longitude; the standard USGS topographic quadrangle is 7.5 minutes on a side at a scale of 1:24,000.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.1 (grade 8) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 1.2 (grade 6)
A rectangular map area bounded by lines of latitude and longitude; the standard USGS topographic quadrangle is 7.5 minutes on a side at a scale of 1:24,000.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.1 (grade 8) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 1.2 (grade 6)
quadratEnglish
A square marked on the ground, such as 3 feet on each side, where a scientist counts every living thing.
Grade 3 Life Science: Plants and Animals Together, Lesson 5.4 (grade 3) · Grade 5 Life Science: The Human Body, Lesson 9.2 (grade 5) · Grade 6 Life Science: Animal Design and Behavior, Lesson 9.2 (grade 6) · +3 more
A square marked on the ground, such as 3 feet on each side, where a scientist counts every living thing.
Grade 3 Life Science: Plants and Animals Together, Lesson 5.4 (grade 3) · Grade 5 Life Science: The Human Body, Lesson 9.2 (grade 5) · Grade 6 Life Science: Animal Design and Behavior, Lesson 9.2 (grade 6) · +3 more
quarryEnglish
A place where people dig rock out of the ground. A bone quarry is where they dig out fossil bones.
Grade 2 Earth Science: The Earth's Surface, Lesson 7.1 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.2 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.1 (grade 3) · +3 more
A place where people dig rock out of the ground. A bone quarry is where they dig out fossil bones.
Grade 2 Earth Science: The Earth's Surface, Lesson 7.1 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.2 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.1 (grade 3) · +3 more
quarter moonEnglish
Another name for a half moon, when we see half of the moon’s face lit up.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.2 (grade 1)
Another name for a half moon, when we see half of the moon’s face lit up.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.2 (grade 1)
quick burialEnglish
Being covered by thick sediment fast, before scavengers, air and rot can destroy a dead plant or animal.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.1 (grade 3)
Being covered by thick sediment fast, before scavengers, air and rot can destroy a dead plant or animal.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.1 (grade 3)
R
rachisEnglish
The stiff central shaft of a feather, running from the hollow base (calamus) to the tip.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.4 (grade 7) · Explore Dinosaurs · Ranger, Stop 3.7 (Ages 10–13)
The stiff central shaft of a feather, running from the hollow base (calamus) to the tip.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.4 (grade 7) · Explore Dinosaurs · Ranger, Stop 3.7 (Ages 10–13)
radiation fogEnglish
Fog that forms on clear, calm nights when the ground loses heat to the sky and cools the air just above it.
Grade 4 Earth Science: Weather and Water, Lesson 3.3 (grade 4)
Fog that forms on clear, calm nights when the ground loses heat to the sky and cools the air just above it.
Grade 4 Earth Science: Weather and Water, Lesson 3.3 (grade 4)
radio signalEnglish
An invisible wave that travels at the speed of light, about 300,000 kilometers (186,000 miles) per second, used to send messages and pictures across space.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.4 (grade 5)
An invisible wave that travels at the speed of light, about 300,000 kilometers (186,000 miles) per second, used to send messages and pictures across space.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.4 (grade 5)
radioactive decayEnglish
The change of an unstable nucleus into a different nucleus, giving off a particle or energy as it does so.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.1 (grade 7) · Explore Dinosaurs · Expert, Stop 4.9 (Ages 14+)
The change of an unstable nucleus into a different nucleus, giving off a particle or energy as it does so.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.1 (grade 7) · Explore Dinosaurs · Expert, Stop 4.9 (Ages 14+)
radiometric datingEnglish
Calculating an age from the measured amounts of a parent isotope and its daughter in a rock, using the half-life.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.2 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.3 (grade 8) · Explore Dinosaurs · Ranger, Stop 4.8 (Ages 10–13)
Calculating an age from the measured amounts of a parent isotope and its daughter in a rock, using the half-life.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.2 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.3 (grade 8) · Explore Dinosaurs · Ranger, Stop 4.8 (Ages 10–13)
radiosondeEnglish
A small instrument package carried up by a weather balloon that radios back temperature, humidity and pressure while its position is tracked to find the wind.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.1 (grade 8)
A small instrument package carried up by a weather balloon that radios back temperature, humidity and pressure while its position is tracked to find the wind.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.1 (grade 8)
radius and ulnaEnglish
The two bones of the forearm, between the elbow and the wrist. The same pair is found in a bird’s wing.
Grade 5 Life Science: The Human Body, Lesson 9.4 (grade 5)
The two bones of the forearm, between the elbow and the wrist. The same pair is found in a bird’s wing.
Grade 5 Life Science: The Human Body, Lesson 9.4 (grade 5)
radulaEnglish
A ribbon-like tongue covered with rows of tiny teeth that a snail uses to scrape up food.
Grade 4 Life Science: Classification, Lesson 3.3 (grade 4)
A ribbon-like tongue covered with rows of tiny teeth that a snail uses to scrape up food.
Grade 4 Life Science: Classification, Lesson 3.3 (grade 4)
rainEnglish
Drops of water that fall from the clouds to the ground.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.1 (grade K) · Grade 1 Geography: Maps and Journeys, Lesson 4.2 (grade 1)
Drops of water that fall from the clouds to the ground.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.1 (grade K) · Grade 1 Geography: Maps and Journeys, Lesson 4.2 (grade 1)
rain cloudEnglish
A cloud that has grown so full of water drops that the drops fall as rain.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 4.4 (grade 1)
A cloud that has grown so full of water drops that the drops fall as rain.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 4.4 (grade 1)
rain gaugeEnglish
A cup or tube with a ruler on it that catches rain and shows how much fell.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 4.3 (grade 1) · Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.2 (grade 1) · Grade 4 Earth Science: Weather and Water, Lesson 9.1 (grade 4) · +1 more
A cup or tube with a ruler on it that catches rain and shows how much fell.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 4.3 (grade 1) · Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.2 (grade 1) · Grade 4 Earth Science: Weather and Water, Lesson 9.1 (grade 4) · +1 more
rain shadowEnglish
A dry area on the leeward side of a mountain range, where the air has already dropped most of its water on the windward side.
Grade 4 Earth Science: Weather and Water, Lesson 8.2 (grade 4) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 4.3 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 5.3 (grade 6) · +3 more
A dry area on the leeward side of a mountain range, where the air has already dropped most of its water on the windward side.
Grade 4 Earth Science: Weather and Water, Lesson 8.2 (grade 4) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 4.3 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 5.3 (grade 6) · +3 more
random samplingEnglish
Choosing where to sample by chance (dice, random numbers) so that the counter’s own choices do not bias the results.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 9.2 (grade 8)
Choosing where to sample by chance (dice, random numbers) so that the counter’s own choices do not bias the results.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 9.2 (grade 8)
rankEnglish
One level of classification, such as kingdom, class or genus. Each rank is a group inside the rank above it.
Grade 4 Life Science: Classification, Lesson 1.2 (grade 4)
One level of classification, such as kingdom, class or genus. Each rank is a group inside the rank above it.
Grade 4 Life Science: Classification, Lesson 1.2 (grade 4)
rapid burialEnglish
Covering a body with sediment within days or weeks, before decay and scavengers destroy it. Nearly every good fossil required it.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.2 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 3.1 (grade 7) · Explore Dinosaurs · Ranger, Stop 4.5 (Ages 10–13)
Covering a body with sediment within days or weeks, before decay and scavengers destroy it. Nearly every good fossil required it.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.2 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 3.1 (grade 7) · Explore Dinosaurs · Ranger, Stop 4.5 (Ages 10–13)
rapidsEnglish
A part of a river where the water runs fast and rough over rocks.
Grade 2 Earth Science: The Earth's Surface, Lesson 8.1 (grade 2) · Grade 2 Geography: Our Country, Coast to Coast, Lesson 3.4 (grade 2) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 6.4 (grade 8)
A part of a river where the water runs fast and rough over rocks.
Grade 2 Earth Science: The Earth's Surface, Lesson 8.1 (grade 2) · Grade 2 Geography: Our Country, Coast to Coast, Lesson 3.4 (grade 2) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 6.4 (grade 8)
raster dataEnglish
A map stored as a grid of equal cells, each holding one value such as elevation or land cover; satellite images and elevation models are rasters.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.3 (grade 8) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 7.4 (grade 8)
A map stored as a grid of equal cells, each holding one value such as elevation or land cover; satellite images and elevation models are rasters.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.3 (grade 8) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 7.4 (grade 8)
ravenEnglish
A big, shiny black bird with a thick beak and a deep, croaking voice. It is bigger than a crow and very smart.
Grade 1 Life Science: Animal Homes and Habits, Lesson 4.4 (grade 1)
A big, shiny black bird with a thick beak and a deep, croaking voice. It is bigger than a crow and very smart.
Grade 1 Life Science: Animal Homes and Habits, Lesson 4.4 (grade 1)
raysEnglish
Bright streaks that spread out from some craters, made of dust and rock thrown out by the crash.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.4 (grade 1)
Bright streaks that spread out from some craters, made of dust and rock thrown out by the crash.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.4 (grade 1)
reapEnglish
To cut and gather a crop when it is ripe.
Grade 3 Life Science: Plants and Animals Together, Lesson 2.4 (grade 3)
To cut and gather a crop when it is ripe.
Grade 3 Life Science: Plants and Animals Together, Lesson 2.4 (grade 3)
recessiveEnglish
Describes an allele whose trait shows only when two copies are present, with no dominant allele. Written with a lowercase letter.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.2 (grade 8)
Describes an allele whose trait shows only when two copies are present, with no dominant allele. Written with a lowercase letter.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.2 (grade 8)
rechargeEnglish
Rain or snowmelt that soaks down through the soil and refills the groundwater.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.1 (grade 8)
Rain or snowmelt that soaks down through the soil and refills the groundwater.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.1 (grade 8)
recipientEnglish
The patient who receives the donated blood.
Grade 5 Life Science: The Human Body, Lesson 3.4 (grade 5)
The patient who receives the donated blood.
Grade 5 Life Science: The Human Body, Lesson 3.4 (grade 5)
reclamationEnglish
Restoring mined land to a stable, useful condition: regrading the ground, replacing topsoil, controlling water and establishing plants so that the land can be pasture, forest, wetland, cropland or a park.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.4 (grade 8)
Restoring mined land to a stable, useful condition: regrading the ground, replacing topsoil, controlling water and establishing plants so that the land can be pasture, forest, wetland, cropland or a park.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.4 (grade 8)
reclamation bondEnglish
Money a mining company must deposit before it digs, enough to pay for reclamation if the company fails to do it. The bond is returned in stages only after the land is regraded, replanted and proven to hold its vegetation.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.4 (grade 8)
Money a mining company must deposit before it digs, enough to pay for reclamation if the company fails to do it. The bond is returned in stages only after the land is regraded, replanted and proven to hold its vegetation.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.4 (grade 8)
recovery timeEnglish
How long it takes for breathing rate and pulse to return to their resting numbers after exercise.
Grade 5 Life Science: The Human Body, Lesson 4.3 (grade 5)
How long it takes for breathing rate and pulse to return to their resting numbers after exercise.
Grade 5 Life Science: The Human Body, Lesson 4.3 (grade 5)
recycleEnglish
To send used things, like cans and paper, to be made into new things.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 8.2 (grade K)
To send used things, like cans and paper, to be made into new things.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 8.2 (grade K)
red blood cellEnglish
A tiny, round, dented disk filled with hemoglobin that carries oxygen from the lungs to the body. Red cells are by far the most common blood cells.
Grade 5 Life Science: The Human Body, Lesson 3.3 (grade 5)
A tiny, round, dented disk filled with hemoglobin that carries oxygen from the lungs to the body. Red cells are by far the most common blood cells.
Grade 5 Life Science: The Human Body, Lesson 3.3 (grade 5)
reflectEnglish
To bounce light back. The Moon makes no light of its own; moonlight is sunlight reflected from the Moon’s rocky surface.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.1 (grade 5)
To bounce light back. The Moon makes no light of its own; moonlight is sunlight reflected from the Moon’s rocky surface.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.1 (grade 5)
reflecting telescopeEnglish
A telescope that uses a curved mirror, instead of a lens, to gather light and form an image.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.3 (grade 5)
A telescope that uses a curved mirror, instead of a lens, to gather light and form an image.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.3 (grade 5)
reflecting telescope (reflector)English
A telescope that uses a curved mirror instead of a front lens to gather light and bring it to a focus. Hubble and Webb are reflectors.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.2 (grade 5)
A telescope that uses a curved mirror instead of a front lens to gather light and bring it to a focus. Hubble and Webb are reflectors.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.2 (grade 5)
reflexEnglish
A quick, automatic action the body makes without waiting for you to decide, such as blinking or pulling your hand off something hot.
Grade 5 Life Science: The Human Body, Lesson 6.1 (grade 5) · Grade 6 Life Science: Animal Design and Behavior, Lesson 5.4 (grade 6)
A quick, automatic action the body makes without waiting for you to decide, such as blinking or pulling your hand off something hot.
Grade 5 Life Science: The Human Body, Lesson 6.1 (grade 5) · Grade 6 Life Science: Animal Design and Behavior, Lesson 5.4 (grade 6)
reflex arcEnglish
The short path a reflex message takes: from a sense receptor, along a sensory nerve to the spinal cord, and back out along a motor nerve to a muscle.
Grade 5 Life Science: The Human Body, Lesson 6.1 (grade 5)
The short path a reflex message takes: from a sense receptor, along a sensory nerve to the spinal cord, and back out along a motor nerve to a muscle.
Grade 5 Life Science: The Human Body, Lesson 6.1 (grade 5)
refracting telescope (refractor)English
A telescope that uses glass lenses to bend light and bring it to a focus.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.1 (grade 5)
A telescope that uses glass lenses to bend light and bring it to a focus.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.1 (grade 5)
refugeEnglish
A safe place to run to when you are in danger.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.4 (grade 2) · Explore Animals · Ranger, Stop 1.10 (Ages 10–13)
A safe place to run to when you are in danger.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.4 (grade 2) · Explore Animals · Ranger, Stop 1.10 (Ages 10–13)
regenerateEnglish
To grow back a lost body part, such as a leg or claw.
Grade 4 Life Science: Classification, Lesson 3.2 (grade 4)
To grow back a lost body part, such as a leg or claw.
Grade 4 Life Science: Classification, Lesson 3.2 (grade 4)
registered nurseEnglish
A licensed health worker who cares for patients day and night, gives medicines, watches for changes and teaches patients and families.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.1 (grade 8)
A licensed health worker who cares for patients day and night, gives medicines, watches for changes and teaches patients and families.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.1 (grade 8)
regurgitateEnglish
To bring food back up from the stomach and out through the mouth. Owls regurgitate their pellets.
Grade 3 Life Science: Plants and Animals Together, Lesson 4.3 (grade 3) · Grade 7 Life Science: Cells and Microbes, Lesson 8.3 (grade 7)
To bring food back up from the stomach and out through the mouth. Owls regurgitate their pellets.
Grade 3 Life Science: Plants and Animals Together, Lesson 4.3 (grade 3) · Grade 7 Life Science: Cells and Microbes, Lesson 8.3 (grade 7)
relative ageEnglish
Whether one thing is older or younger than another, with no number of years attached.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.2 (grade 7)
Whether one thing is older or younger than another, with no number of years attached.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.2 (grade 7)
releaseEnglish
To let an animal go free again, back in the place where it came from.
Grade 2 Life Science: Animal Families, Lesson 4.4 (grade 2)
To let an animal go free again, back in the place where it came from.
Grade 2 Life Science: Animal Families, Lesson 4.4 (grade 2)
REM sleepEnglish
Rapid eye movement sleep: the stage when the eyes dart back and forth under the lids, the brain is very active and most vivid dreams happen.
Grade 5 Life Science: The Human Body, Lesson 6.4 (grade 5) · Grade 11 Physical Education & Health, Lesson 1.1 (grade 11)
Rapid eye movement sleep: the stage when the eyes dart back and forth under the lids, the brain is very active and most vivid dreams happen.
Grade 5 Life Science: The Human Body, Lesson 6.4 (grade 5) · Grade 11 Physical Education & Health, Lesson 1.1 (grade 11)
reptileEnglish
An animal with a backbone and dry scaly skin that breathes air, like a turtle, lizard or crocodile.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.1 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 7.1 (grade K) · Explore Animals · Ranger, Stop 3.1 (Ages 10–13) · +3 more
An animal with a backbone and dry scaly skin that breathes air, like a turtle, lizard or crocodile.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.1 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 7.1 (grade K) · Explore Animals · Ranger, Stop 3.1 (Ages 10–13) · +3 more
reservoirEnglish
A lake made by a dam, where water is stored.
Grade 4 Earth Science: Weather and Water, Lesson 6.1 (grade 4) · Grade 2 Engineering & Physics, Lesson 5.1 (grade 2) · Grade 3 Engineering & Physics, Lesson 5.1 (grade 3) · +3 more
A lake made by a dam, where water is stored.
Grade 4 Earth Science: Weather and Water, Lesson 6.1 (grade 4) · Grade 2 Engineering & Physics, Lesson 5.1 (grade 2) · Grade 3 Engineering & Physics, Lesson 5.1 (grade 3) · +3 more
reservoir pressureEnglish
The push of fluid in the pores of a rock, which drives oil up a well. When too many wells drain a field, pressure drops and the wells slow.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.2 (grade 8)
The push of fluid in the pores of a rock, which drives oil up a well. When too many wells drain a field, pressure drops and the wells slow.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.2 (grade 8)
reservoir rockEnglish
A rock with connected pore spaces, such as sandstone or porous limestone, that holds oil, gas or water the way a sponge holds water.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.3 (grade 8) · Geography and Commerce: Sea Lanes, Straits and Trade Routes, Lesson 4.4 (grade 9–12) · Grade 7 Geography: Regions of the World, Lesson 3.4 (grade 7)
A rock with connected pore spaces, such as sandstone or porous limestone, that holds oil, gas or water the way a sponge holds water.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.3 (grade 8) · Geography and Commerce: Sea Lanes, Straits and Trade Routes, Lesson 4.4 (grade 9–12) · Grade 7 Geography: Regions of the World, Lesson 3.4 (grade 7)
residual volumeEnglish
The air that always stays in the lungs, even after you breathe out as hard as you can. It keeps the tiny air sacs from collapsing.
Grade 5 Life Science: The Human Body, Lesson 4.2 (grade 5)
The air that always stays in the lungs, even after you breathe out as hard as you can. It keeps the tiny air sacs from collapsing.
Grade 5 Life Science: The Human Body, Lesson 4.2 (grade 5)
restateEnglish
Saying back what someone claimed in your own words and checking that you got it right, before you answer.
Grade 7 Earth Science: Earth History and the Flood, Lesson 8.3 (grade 7)
Saying back what someone claimed in your own words and checking that you got it right, before you answer.
Grade 7 Earth Science: Earth History and the Flood, Lesson 8.3 (grade 7)
resting heart rateEnglish
Your heart rate when you have been sitting or lying quietly for several minutes.
Grade 5 Life Science: The Human Body, Lesson 3.2 (grade 5) · Grade 4 Physical Education & Health, Lesson 5.2 (grade 4) · Grade 6 Physical Education & Health, Lesson 5.1 (grade 6) · +1 more
Your heart rate when you have been sitting or lying quietly for several minutes.
Grade 5 Life Science: The Human Body, Lesson 3.2 (grade 5) · Grade 4 Physical Education & Health, Lesson 5.2 (grade 4) · Grade 6 Physical Education & Health, Lesson 5.1 (grade 6) · +1 more
reteEnglish
The lacy, cut-out star map on the front of an astrolabe, with pointers for bright stars. It turns to show the sky at any hour.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.2 (grade 5)
The lacy, cut-out star map on the front of an astrolabe, with pointers for bright stars. It turns to show the sky at any hour.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.2 (grade 5)
retinaEnglish
The thin layer at the back of the eye, full of light-sensing cells called rods and cones.
Grade 5 Life Science: The Human Body, Lesson 7.1 (grade 5) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.2 (grade 8)
The thin layer at the back of the eye, full of light-sensing cells called rods and cones.
Grade 5 Life Science: The Human Body, Lesson 7.1 (grade 5) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.2 (grade 8)
retrograde motionEnglish
The way a planet such as Mars seems to stop and slide backward among the stars for a while, because Earth is passing it.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.1 (grade 5)
The way a planet such as Mars seems to stop and slide backward among the stars for a while, because Earth is passing it.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.1 (grade 5)
reviewEnglish
Looking again at what you have learned so you remember it better and see it more clearly.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 8.4 (grade 3)
Looking again at what you have learned so you remember it better and see it more clearly.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 8.4 (grade 3)
revolutionEnglish
One complete trip of the earth around the sun. One revolution takes about 365¼ days, one year.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.3 (grade 5) · Explore Heroines of History and Faith, Stop 3.6 (Ages 7–9)
One complete trip of the earth around the sun. One revolution takes about 365¼ days, one year.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.3 (grade 5) · Explore Heroines of History and Faith, Stop 3.6 (Ages 7–9)
rhizoidEnglish
A thin, hairlike thread that holds a moss to soil, bark or rock. It is not a true root.
Grade 4 Life Science: Classification, Lesson 6.1 (grade 4)
A thin, hairlike thread that holds a moss to soil, bark or rock. It is not a true root.
Grade 4 Life Science: Classification, Lesson 6.1 (grade 4)
ribbon testEnglish
Pressing moist soil between thumb and finger to push out a ribbon; the longer the ribbon, the more clay the soil holds.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.1 (grade 8)
Pressing moist soil between thumb and finger to push out a ribbon; the longer the ribbon, the more clay the soil holds.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.1 (grade 8)
ribletsEnglish
Tiny parallel ridges running in the direction of flow. Shark denticles have them, and engineers copy them to reduce friction drag.
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.2 (grade 6)
Tiny parallel ridges running in the direction of flow. Shark denticles have them, and engineers copy them to reduce friction drag.
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.2 (grade 6)
ribosomeEnglish
A tiny structure that builds proteins by following instructions copied from the DNA. Ribosomes float free in the cytoplasm or sit on the rough endoplasmic reticulum.
Grade 7 Life Science: Cells and Microbes, Lesson 2.2 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.4 (grade 8)
A tiny structure that builds proteins by following instructions copied from the DNA. Ribosomes float free in the cytoplasm or sit on the rough endoplasmic reticulum.
Grade 7 Life Science: Cells and Microbes, Lesson 2.2 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.4 (grade 8)
rimEnglish
The raised edge around a crater, like the edge of a bowl.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.4 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 8.4 (grade 2) · Grade 5 Engineering & Physics, Lesson 9.1 (grade 5) · +2 more
The raised edge around a crater, like the edge of a bowl.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.4 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 8.4 (grade 2) · Grade 5 Engineering & Physics, Lesson 9.1 (grade 5) · +2 more
ripple marksEnglish
Small wavy ridges in sand made by moving water or wind. Found in rock, they show that the sand was laid down by moving water.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.4 (grade 3)
Small wavy ridges in sand made by moving water or wind. Found in rock, they show that the sand was laid down by moving water.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.4 (grade 3)
rising pressureEnglish
Air pressure going up over hours or days. It often means fair weather is coming.
Grade 4 Earth Science: Weather and Water, Lesson 2.2 (grade 4)
Air pressure going up over hours or days. It often means fair weather is coming.
Grade 4 Earth Science: Weather and Water, Lesson 2.2 (grade 4)
rivalEnglish
A person who is trying to beat you at the same thing.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.1 (grade 3) · Explore Dinosaurs, Stop 2.6 (Ages 7–9)
A person who is trying to beat you at the same thing.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.1 (grade 3) · Explore Dinosaurs, Stop 2.6 (Ages 7–9)
riverEnglish
A big stream of water that flows downhill in a long path to the sea or a big lake.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.1 (grade 1) · Grade 1 Geography: Maps and Journeys, Lesson 4.3 (grade 1) · Grade 1 Geography: Maps and Journeys, Lesson 8.3 (grade 1) · +3 more
A big stream of water that flows downhill in a long path to the sea or a big lake.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.1 (grade 1) · Grade 1 Geography: Maps and Journeys, Lesson 4.3 (grade 1) · Grade 1 Geography: Maps and Journeys, Lesson 8.3 (grade 1) · +3 more
river stoneEnglish
A rock that has been rolled and rubbed by moving water until its corners wore away.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.3 (grade K)
A rock that has been rolled and rubbed by moving water until its corners wore away.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.3 (grade K)
road cutEnglish
A place where builders have cut or blasted through a hill to make room for a road, showing the rock layers inside.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.4 (grade 3) · Grade 7 Earth Science: Earth History and the Flood, Lesson 9.1 (grade 7)
A place where builders have cut or blasted through a hill to make room for a road, showing the rock layers inside.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.4 (grade 3) · Grade 7 Earth Science: Earth History and the Flood, Lesson 9.1 (grade 7)
rockEnglish
A hard, solid piece of the earth. Rocks can be as big as a mountain or as small as a pebble.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 1.1 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.1 (grade K) · Kindergarten Engineering & Physics, Lesson 3.4 (grade K) · +1 more
A hard, solid piece of the earth. Rocks can be as big as a mountain or as small as a pebble.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 1.1 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.1 (grade K) · Kindergarten Engineering & Physics, Lesson 3.4 (grade K) · +1 more
rock cycleEnglish
The ways rocks change from one kind into another: igneous, sedimentary and metamorphic, over and over.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.4 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.1 (grade 3)
The ways rocks change from one kind into another: igneous, sedimentary and metamorphic, over and over.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.4 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.1 (grade 3)
rock familyEnglish
One of the three main groups of rocks: igneous, sedimentary or metamorphic, sorted by how they formed.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 8.4 (grade 3)
One of the three main groups of rocks: igneous, sedimentary or metamorphic, sorted by how they formed.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 8.4 (grade 3)
rock hunterEnglish
Someone who goes outside to look for rocks and look at them closely. Scientists who study rocks are called geologists.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.1 (grade K)
Someone who goes outside to look for rocks and look at them closely. Scientists who study rocks are called geologists.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.1 (grade K)
rocketEnglish
A tall machine that pushes out hot gas very fast to blast up into space.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.3 (grade 1) · Grade 5 Engineering & Physics, Lesson 7.4 (grade 5)
A tall machine that pushes out hot gas very fast to blast up into space.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.3 (grade 1) · Grade 5 Engineering & Physics, Lesson 7.4 (grade 5)
rockslideEnglish
A mass of rock that breaks loose and slides fast along a surface such as a bedding plane or crack.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.3 (grade 6)
A mass of rock that breaks loose and slides fast along a surface such as a bedding plane or crack.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.3 (grade 6)
rods and conesEnglish
The light-sensing cells of the retina. Rods work in dim light; cones sense color and fine detail in bright light.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.2 (grade 8)
The light-sensing cells of the retina. Rods work in dim light; cones sense color and fine detail in bright light.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.2 (grade 8)
roof supportEnglish
Pillars, timber, steel roof bolts and hydraulic shields that hold up the rock above a mine opening. Roof falls have long been the leading cause of underground mining deaths.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.3 (grade 8)
Pillars, timber, steel roof bolts and hydraulic shields that hold up the rock above a mine opening. Roof falls have long been the leading cause of underground mining deaths.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.3 (grade 8)
room-and-pillarEnglish
An underground method in which miners remove ore in rooms and leave pillars of rock standing to hold up the roof, common in coal, salt and limestone mines.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.2 (grade 8)
An underground method in which miners remove ore in rooms and leave pillars of rock standing to hold up the roof, common in coal, salt and limestone mines.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.2 (grade 8)
roostEnglish
A place where bats hang up to rest, such as a cave ceiling.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.3 (grade 2) · Explore Animals, Stop 1.4 (Ages 7–9) · Grade 3 Gardening & Animals, Lesson 6.1 (grade 3)
A place where bats hang up to rest, such as a cave ceiling.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.3 (grade 2) · Explore Animals, Stop 1.4 (Ages 7–9) · Grade 3 Gardening & Animals, Lesson 6.1 (grade 3)
rootEnglish
The part of a plant that grows down into the soil to drink water and hold the plant tight.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.4 (grade K) · Grade 1 Gardening & Animals, Lesson 5.2 (grade 1) · Kindergarten Gardening & Animals, Lesson 5.2 (grade K) · +3 more
The part of a plant that grows down into the soil to drink water and hold the plant tight.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.4 (grade K) · Grade 1 Gardening & Animals, Lesson 5.2 (grade 1) · Kindergarten Gardening & Animals, Lesson 5.2 (grade K) · +3 more
rotEnglish
When worms, bugs and tiny living things slowly break down old leaves and plants until they turn back into soil.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 8.2 (grade K) · Grade 1 Gardening & Animals, Lesson 3.3 (grade 1)
When worms, bugs and tiny living things slowly break down old leaves and plants until they turn back into soil.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 8.2 (grade K) · Grade 1 Gardening & Animals, Lesson 3.3 (grade 1)
rotary drillingEnglish
Drilling by spinning a toothed bit on the end of a turning pipe while fluid is pumped down the pipe to carry the rock chips back up.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.2 (grade 8)
Drilling by spinning a toothed bit on the end of a turning pipe while fluid is pumped down the pipe to carry the rock chips back up.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.2 (grade 8)
rotary motorEnglish
A motor in which one part (the rotor) spins inside a fixed part (the stator). The bacterial flagellum is driven by one.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.3 (grade 8)
A motor in which one part (the rotor) spins inside a fixed part (the stator). The bacterial flagellum is driven by one.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 4.3 (grade 8)
rotationEnglish
The spinning of the earth on its axis. One rotation takes about 24 hours and gives us day and night.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.3 (grade 5) · Body Mechanics of Sport, Lesson 8.4 (grade 4–7) · Sports & Games of the World, Lesson 7.3 (grade 4–7) · +2 more
The spinning of the earth on its axis. One rotation takes about 24 hours and gives us day and night.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.3 (grade 5) · Body Mechanics of Sport, Lesson 8.4 (grade 4–7) · Sports & Games of the World, Lesson 7.3 (grade 4–7) · +2 more
roughEnglish
Bumpy or scratchy, with edges and points you can feel.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.3 (grade K)
Bumpy or scratchy, with edges and points you can feel.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.3 (grade K)
roundedEnglish
Smooth, with the corners worn off, like an egg or a ball.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.3 (grade 1)
Smooth, with the corners worn off, like an egg or a ball.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.3 (grade 1)
rowEnglish
Things in a straight line, side by side. An egg carton has two rows of cups.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 1.2 (grade 1) · Explore Crafts and Making, Stop 2.3 (Ages 7–9) · Kindergarten Gardening & Animals, Lesson 7.3 (grade K) · +3 more
Things in a straight line, side by side. An egg carton has two rows of cups.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 1.2 (grade 1) · Explore Crafts and Making, Stop 2.3 (Ages 7–9) · Kindergarten Gardening & Animals, Lesson 7.3 (grade K) · +3 more
runaway subductionEnglish
A sinking plate heats and weakens the mantle rock around it, which lets it sink faster, which weakens the rock more, so the sinking speeds up without limit until the plate is gone.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.4 (grade 6)
A sinking plate heats and weakens the mantle rock around it, which lets it sink faster, which weakens the rock more, so the sinking speeds up without limit until the plate is gone.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.4 (grade 6)
runoffEnglish
Rain or melted snow that flows over the ground into streams, rivers, lakes and the sea.
Grade 4 Earth Science: Weather and Water, Lesson 1.1 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 6.3 (grade 4) · Grade 6 Earth Science: The Dynamic Earth, Lesson 9.1 (grade 6) · +2 more
Rain or melted snow that flows over the ground into streams, rivers, lakes and the sea.
Grade 4 Earth Science: Weather and Water, Lesson 1.1 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 6.3 (grade 4) · Grade 6 Earth Science: The Dynamic Earth, Lesson 9.1 (grade 6) · +2 more
runupEnglish
The highest point above normal sea level that a tsunami reaches on land.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.4 (grade 6)
The highest point above normal sea level that a tsunami reaches on land.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.4 (grade 6)
rustEnglish
The flaky red-brown stuff that forms when iron joins with oxygen from the air and water.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.2 (grade 3) · Grade 4 Gardening & Animals, Lesson 8.2 (grade 4) · Grade 6 Gardening & Animals, Lesson 8.2 (grade 6)
The flaky red-brown stuff that forms when iron joins with oxygen from the air and water.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.2 (grade 3) · Grade 4 Gardening & Animals, Lesson 8.2 (grade 4) · Grade 6 Gardening & Animals, Lesson 8.2 (grade 6)
S
S waveEnglish
Secondary wave: a slower seismic wave that shakes rock from side to side. It can travel only through solids.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.1 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 4.3 (grade 6)
Secondary wave: a slower seismic wave that shakes rock from side to side. It can travel only through solids.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.1 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 4.3 (grade 6)
Saffir-Simpson scaleEnglish
A scale from Category 1 to Category 5 that sorts hurricanes by their steady wind speed.
Grade 4 Earth Science: Weather and Water, Lesson 4.1 (grade 4)
A scale from Category 1 to Category 5 that sorts hurricanes by their steady wind speed.
Grade 4 Earth Science: Weather and Water, Lesson 4.1 (grade 4)
saguaroEnglish
A giant cactus with arms that grows in the Sonoran Desert of Arizona and Mexico. Say it “suh-WAH-roh.”
Grade 1 Life Science: Animal Homes and Habits, Lesson 4.3 (grade 1) · Grade 3 Life Science: Plants and Animals Together, Lesson 3.3 (grade 3)
A giant cactus with arms that grows in the Sonoran Desert of Arizona and Mexico. Say it “suh-WAH-roh.”
Grade 1 Life Science: Animal Homes and Habits, Lesson 4.3 (grade 1) · Grade 3 Life Science: Plants and Animals Together, Lesson 3.3 (grade 3)
sailsEnglish
The long arms of a windmill. The wind pushes on them and makes them turn.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.3 (grade 1)
The long arms of a windmill. The wind pushes on them and makes them turn.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.3 (grade 1)
salinityEnglish
How much salt is dissolved in water. Ocean water has about 35 grams of salt in every kilogram of water.
Grade 4 Earth Science: Weather and Water, Lesson 7.3 (grade 4) · Geography and Commerce: Sea Lanes, Straits and Trade Routes, Lesson 3.3 (grade 9–12)
How much salt is dissolved in water. Ocean water has about 35 grams of salt in every kilogram of water.
Grade 4 Earth Science: Weather and Water, Lesson 7.3 (grade 4) · Geography and Commerce: Sea Lanes, Straits and Trade Routes, Lesson 3.3 (grade 9–12)
salivaEnglish
The watery juice made in the mouth that wets food and begins breaking starch down into sugar.
Grade 5 Life Science: The Human Body, Lesson 5.2 (grade 5)
The watery juice made in the mouth that wets food and begins breaking starch down into sugar.
Grade 5 Life Science: The Human Body, Lesson 5.2 (grade 5)
salt domeEnglish
A thick plug of rock salt that has pushed upward through the layers above it, bending them up and making traps for oil along its sides and over its cap.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.2 (grade 8) · High School Geology, Lesson 7.4 (grade 9–12)
A thick plug of rock salt that has pushed upward through the layers above it, bending them up and making traps for oil along its sides and over its cap.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.2 (grade 8) · High School Geology, Lesson 7.4 (grade 9–12)
saltationEnglish
The hopping of sand grains along the ground in the wind. A grain lifts, flies a short arc, lands and knocks other grains into the air. Most sand moves this way.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.3 (grade 6) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.1 (grade 8)
The hopping of sand grains along the ground in the wind. A grain lifts, flies a short arc, lands and knocks other grains into the air. Most sand moves this way.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.3 (grade 6) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.1 (grade 8)
sample labelEnglish
A tag that travels with a sample giving its site number, date, location and collector; a sample without one is only a rock.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.2 (grade 8)
A tag that travels with a sample giving its site number, date, location and collector; a sample without one is only a rock.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.2 (grade 8)
San Andreas FaultEnglish
A very long fault that runs through California. The ground slipped along it in 1906.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.1 (grade 2)
A very long fault that runs through California. The ground slipped along it in 1906.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.1 (grade 2)
sandEnglish
Tiny grains of rock, so small they look like sugar or salt.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 1.3 (grade 1) · Grade 1 Earth Science: Rocks, Water and Weather, Lesson 2.1 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 6.3 (grade 2) · +3 more
Tiny grains of rock, so small they look like sugar or salt.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 1.3 (grade 1) · Grade 1 Earth Science: Rocks, Water and Weather, Lesson 2.1 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 6.3 (grade 2) · +3 more
sand duneEnglish
A hill of sand at the top of a beach, piled up by the wind and often held in place by grass.
Grade 2 Earth Science: The Earth's Surface, Lesson 6.4 (grade 2)
A hill of sand at the top of a beach, piled up by the wind and often held in place by grass.
Grade 2 Earth Science: The Earth's Surface, Lesson 6.4 (grade 2)
sandstoneEnglish
A hard rock made of sand grains stuck together. It makes a strong roof over Mammoth Cave.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.1 (grade 2) · Grade 2 Earth Science: The Earth's Surface, Lesson 7.1 (grade 2) · Grade 2 Earth Science: The Earth's Surface, Lesson 8.2 (grade 2) · +3 more
A hard rock made of sand grains stuck together. It makes a strong roof over Mammoth Cave.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.1 (grade 2) · Grade 2 Earth Science: The Earth's Surface, Lesson 7.1 (grade 2) · Grade 2 Earth Science: The Earth's Surface, Lesson 8.2 (grade 2) · +3 more
Saurischia and OrnithischiaEnglish
The two big groups of dinosaurs, named by Harry Seeley in 1887. Saurischians are “lizard-hipped” and ornithischians are “bird-hipped,” named for the shape of their hip bones.
Grade 4 Life Science: Classification, Lesson 7.1 (grade 4)
The two big groups of dinosaurs, named by Harry Seeley in 1887. Saurischians are “lizard-hipped” and ornithischians are “bird-hipped,” named for the shape of their hip bones.
Grade 4 Life Science: Classification, Lesson 7.1 (grade 4)
saurischian and ornithischianEnglish
Two hip arrangements used since 1887 to sort dinosaurs. Saurischian (“lizard-hipped”) hips have the pubis pointing forward; ornithischian (“bird-hipped”) hips have it pointing backward along the ischium.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.1 (grade 7)
Two hip arrangements used since 1887 to sort dinosaurs. Saurischian (“lizard-hipped”) hips have the pubis pointing forward; ornithischian (“bird-hipped”) hips have it pointing backward along the ischium.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.1 (grade 7)
scablandEnglish
Bare, rocky land stripped of its soil, where channels have been cut into hard basalt. In eastern Washington the scablands cover about 40,000 square kilometers.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.1 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 4.4 (grade 7)
Bare, rocky land stripped of its soil, where channels have been cut into hard basalt. In eastern Washington the scablands cover about 40,000 square kilometers.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.1 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 4.4 (grade 7)
scale barEnglish
A short line on a drawing labeled with a real length, such as 1 m, so that a reader can tell the true size of anything drawn.
Grade 7 Earth Science: Earth History and the Flood, Lesson 8.4 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 9.1 (grade 7) · Explore Travel and Faraway Places · Expert, Stop 1.4 (Ages 14+) · +3 more
A short line on a drawing labeled with a real length, such as 1 m, so that a reader can tell the true size of anything drawn.
Grade 7 Earth Science: Earth History and the Flood, Lesson 8.4 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 9.1 (grade 7) · Explore Travel and Faraway Places · Expert, Stop 1.4 (Ages 14+) · +3 more
scale modelEnglish
A copy of something made larger or smaller, with every part shrunk or grown by the same amount, such as 1 inch for every foot.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.3 (grade 3) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.2 (grade 5) · Grade 6 Life Science: Animal Design and Behavior, Lesson 8.4 (grade 6) · +1 more
A copy of something made larger or smaller, with every part shrunk or grown by the same amount, such as 1 inch for every foot.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.3 (grade 3) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.2 (grade 5) · Grade 6 Life Science: Animal Design and Behavior, Lesson 8.4 (grade 6) · +1 more
scale objectEnglish
Something of known size, such as a ruler or a coin, placed beside a living thing in a photo so others can tell how big it is.
Grade 4 Life Science: Classification, Lesson 8.2 (grade 4)
Something of known size, such as a ruler or a coin, placed beside a living thing in a photo so others can tell how big it is.
Grade 4 Life Science: Classification, Lesson 8.2 (grade 4)
scale treeEnglish
A tall tree with bark covered in diamond-shaped scars like scales, often found as fossils in coal-bearing rocks. No trees quite like them grow today.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.4 (grade 3)
A tall tree with bark covered in diamond-shaped scars like scales, often found as fossils in coal-bearing rocks. No trees quite like them grow today.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.4 (grade 3)
scan samplingEnglish
Recording what an animal is doing at fixed moments, such as every 30 seconds, instead of trying to write down everything continuously.
Grade 7 Life Science: Cells and Microbes, Lesson 9.3 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 9.3 (grade 8)
Recording what an animal is doing at fixed moments, such as every 30 seconds, instead of trying to write down everything continuously.
Grade 7 Life Science: Cells and Microbes, Lesson 9.3 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 9.3 (grade 8)
scavengerEnglish
An animal that eats dead things, such as a gull, crab, beetle or vulture.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.1 (grade 3)
An animal that eats dead things, such as a gull, crab, beetle or vulture.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.1 (grade 3)
scent glandsEnglish
Two small pouches under a skunk’s tail that make and store its smelly, oily spray.
Grade 3 Life Science: Plants and Animals Together, Lesson 6.2 (grade 3)
Two small pouches under a skunk’s tail that make and store its smelly, oily spray.
Grade 3 Life Science: Plants and Animals Together, Lesson 6.2 (grade 3)
scent markingEnglish
Leaving urine or other scent on trees, rocks or snow as a message to other animals, such as “this territory is taken.”
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.2 (grade 6)
Leaving urine or other scent on trees, rocks or snow as a message to other animals, such as “this territory is taken.”
Grade 6 Life Science: Animal Design and Behavior, Lesson 6.2 (grade 6)
schoolEnglish
A big group of fish that swim together, all turning at the same time.
Grade 2 Life Science: Animal Families, Lesson 5.4 (grade 2)
A big group of fish that swim together, all turning at the same time.
Grade 2 Life Science: Animal Families, Lesson 5.4 (grade 2)
scientific theoryEnglish
A broad explanation that ties many observations together and can be tested. It is more than a guess, but each of its claims must still be checked against evidence.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.2 (grade 8)
A broad explanation that ties many observations together and can be tested. It is more than a guess, but each of its claims must still be checked against evidence.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.2 (grade 8)
scratchEnglish
A thin line or groove rubbed into something.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.2 (grade K)
A thin line or groove rubbed into something.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.2 (grade K)
scratch testEnglish
Rubbing one thing against another to see which one leaves a groove. The harder one scratches the softer one.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.1 (grade 3)
Rubbing one thing against another to see which one leaves a groove. The harder one scratches the softer one.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.1 (grade 3)
scripEnglish
An old word for a shepherd’s small bag.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.4 (grade K)
An old word for a shepherd’s small bag.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.4 (grade K)
sculptorEnglish
An artist who makes statues by carving, shaping or building them.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.2 (grade 3) · Explore Dinosaurs · Ranger, Stop 2.5 (Ages 10–13) · Explore Dinosaurs, Stop 2.5 (Ages 7–9)
An artist who makes statues by carving, shaping or building them.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.2 (grade 3) · Explore Dinosaurs · Ranger, Stop 2.5 (Ages 10–13) · Explore Dinosaurs, Stop 2.5 (Ages 7–9)
scutesEnglish
The hard plates that cover a turtle’s shell like tiles. They are made of the same stuff as your fingernails.
Grade 2 Life Science: Animal Families, Lesson 3.4 (grade 2)
The hard plates that cover a turtle’s shell like tiles. They are made of the same stuff as your fingernails.
Grade 2 Life Science: Animal Families, Lesson 3.4 (grade 2)
sea breezeEnglish
A cool wind that blows from the sea onto the land on a sunny day, because the warm air over the land rises.
Grade 4 Earth Science: Weather and Water, Lesson 2.3 (grade 4)
A cool wind that blows from the sea onto the land on a sunny day, because the warm air over the land rises.
Grade 4 Earth Science: Weather and Water, Lesson 2.3 (grade 4)
Sea of GalileeEnglish
A big lake in Israel with hills all around it. Jesus and His disciples sailed on it in fishing boats.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.4 (grade 1) · Explore Travel and Faraway Places · Expert, Stop 4.1 (Ages 14+)
A big lake in Israel with hills all around it. Jesus and His disciples sailed on it in fishing boats.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.4 (grade 1) · Explore Travel and Faraway Places · Expert, Stop 4.1 (Ages 14+)
sea surface temperatureEnglish
How warm or cold the water is at the top of the ocean. Warm currents show up as bands of warmer water.
Grade 4 Earth Science: Weather and Water, Lesson 7.4 (grade 4)
How warm or cold the water is at the top of the ocean. Warm currents show up as bands of warmer water.
Grade 4 Earth Science: Weather and Water, Lesson 7.4 (grade 4)
seafloor spreadingEnglish
The making of new ocean crust at a mid-ocean ridge as plates move apart, recorded by magnetic stripes.
High School Geology, Lesson 2.1 (grade 9–12)
The making of new ocean crust at a mid-ocean ridge as plates move apart, recorded by magnetic stripes.
High School Geology, Lesson 2.1 (grade 9–12)
seakeepingEnglish
How a vessel behaves in waves: how much it rolls, pitches and pounds, and whether the people and animals aboard can bear the motion.
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.2 (grade 7)
How a vessel behaves in waves: how much it rolls, pitches and pounds, and whether the people and animals aboard can bear the motion.
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.2 (grade 7)
seal (cap rock)English
A layer of tight rock, such as shale, salt or anhydrite, that fluids cannot pass through, which keeps oil and gas from rising to the surface.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.3 (grade 8)
A layer of tight rock, such as shale, salt or anhydrite, that fluids cannot pass through, which keeps oil and gas from rising to the surface.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.3 (grade 8)
seamEnglish
A single layer of coal between layers of other rock; also called a coal bed.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.4 (grade 7) · Explore Crafts and Making · Ranger, Stop 1.3 (Ages 10–13) · Explore Crafts and Making, Stop 1.3 (Ages 7–9) · +3 more
A single layer of coal between layers of other rock; also called a coal bed.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.4 (grade 7) · Explore Crafts and Making · Ranger, Stop 1.3 (Ages 10–13) · Explore Crafts and Making, Stop 1.3 (Ages 7–9) · +3 more
sedimentEnglish
Loose bits of rock, sand, mud, shells or plants that can be carried by water or wind and then settle down.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.1 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.4 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.1 (grade 3) · +3 more
Loose bits of rock, sand, mud, shells or plants that can be carried by water or wind and then settle down.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.1 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.4 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.1 (grade 3) · +3 more
sediment loadEnglish
The total amount of sediment a river carries, measured in tonnes per year.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.2 (grade 6) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 2.4 (grade 8)
The total amount of sediment a river carries, measured in tonnes per year.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.2 (grade 6) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 2.4 (grade 8)
sedimentary rockEnglish
Rock made when layers of sediment are buried, pressed together and glued by minerals.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.1 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.1 (grade 3)
Rock made when layers of sediment are buried, pressed together and glued by minerals.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.1 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.1 (grade 3)
seedEnglish
A tiny package from a plant that can grow into a new plant of the same kind. It carries a baby plant and a little lunch inside.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.4 (grade K) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.3 (grade K) · Grade 1 Gardening & Animals, Lesson 1.4 (grade 1) · +3 more
A tiny package from a plant that can grow into a new plant of the same kind. It carries a baby plant and a little lunch inside.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.4 (grade K) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.3 (grade K) · Grade 1 Gardening & Animals, Lesson 1.4 (grade 1) · +3 more
seed leafEnglish
One of the two thick halves inside a peanut or bean seed. Seed leaves store food for the baby plant.
Grade 3 Life Science: Plants and Animals Together, Lesson 1.4 (grade 3) · Grade 4 Life Science: Classification, Lesson 6.3 (grade 4)
One of the two thick halves inside a peanut or bean seed. Seed leaves store food for the baby plant.
Grade 3 Life Science: Plants and Animals Together, Lesson 1.4 (grade 3) · Grade 4 Life Science: Classification, Lesson 6.3 (grade 4)
seed leavesEnglish
The thick parts of a seed that hold stored food for the baby plant. A bean has two of them.
Grade 3 Life Science: Plants and Animals Together, Lesson 2.1 (grade 3)
The thick parts of a seed that hold stored food for the baby plant. A bean has two of them.
Grade 3 Life Science: Plants and Animals Together, Lesson 2.1 (grade 3)
seed podEnglish
The dry fruit that holds a plant’s seeds. A yucca seed pod has rows of flat black seeds inside.
Grade 3 Life Science: Plants and Animals Together, Lesson 3.4 (grade 3)
The dry fruit that holds a plant’s seeds. A yucca seed pod has rows of flat black seeds inside.
Grade 3 Life Science: Plants and Animals Together, Lesson 3.4 (grade 3)
seepEnglish
A place where oil or gas leaks naturally out of the ground, often into a creek or spring.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.1 (grade 8) · Explore Dinosaurs · Expert, Stop 5.9 (Ages 14+) · Explore Dinosaurs · Ranger, Stop 5.9 (Ages 10–13) · +1 more
A place where oil or gas leaks naturally out of the ground, often into a creek or spring.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.1 (grade 8) · Explore Dinosaurs · Expert, Stop 5.9 (Ages 14+) · Explore Dinosaurs · Ranger, Stop 5.9 (Ages 10–13) · +1 more
seismic momentEnglish
A measure of an earthquake’s true size: the stiffness of the rock times the area of the fault that slipped times how far it slipped.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.2 (grade 6)
A measure of an earthquake’s true size: the stiffness of the rock times the area of the fault that slipped times how far it slipped.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.2 (grade 6)
seismic waveEnglish
A vibration that travels through the earth, usually sent out by an earthquake.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.1 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 2.1 (grade 6)
A vibration that travels through the earth, usually sent out by an earthquake.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.1 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 2.1 (grade 6)
seismic wavesEnglish
Vibrations that travel outward from the focus through rock, carrying the earthquake’s energy.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.1 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 3.3 (grade 6)
Vibrations that travel outward from the focus through rock, carrying the earthquake’s energy.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.1 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 3.3 (grade 6)
seismogramEnglish
The record a seismograph makes: a wiggly line showing ground motion against time.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.3 (grade 6)
The record a seismograph makes: a wiggly line showing ground motion against time.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.3 (grade 6)
seismographEnglish
An instrument that records ground shaking as a wiggly line marked with exact times.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.1 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 4.3 (grade 6)
An instrument that records ground shaking as a wiggly line marked with exact times.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.1 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 4.3 (grade 6)
selection pressureEnglish
Anything in the surroundings, such as an antibiotic, that lets some individuals survive and reproduce better than others.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.3 (grade 8)
Anything in the surroundings, such as an antibiotic, that lets some individuals survive and reproduce better than others.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.3 (grade 8)
semicircular canalsEnglish
Three curved, fluid-filled tubes in the inner ear that sense turning and help you keep your balance.
Grade 5 Life Science: The Human Body, Lesson 7.2 (grade 5)
Three curved, fluid-filled tubes in the inner ear that sense turning and help you keep your balance.
Grade 5 Life Science: The Human Body, Lesson 7.2 (grade 5)
senior and junior rightsEnglish
Rights ranked by their priority date. In a shortage the senior (older) right receives its full amount first; junior (newer) rights are cut off in order until the stream runs out.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.4 (grade 8)
Rights ranked by their priority date. In a shortage the senior (older) right receives its full amount first; junior (newer) rights are cut off in order until the stream runs out.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.4 (grade 8)
senseEnglish
A way God made your body to learn about the world. Seeing, hearing, smelling, tasting and touching are your five senses.
Grade 1 Life Science: Animal Homes and Habits, Lesson 8.1 (grade 1) · Kindergarten Life Science: God Made the Animals, Lesson 6.3 (grade K)
A way God made your body to learn about the world. Seeing, hearing, smelling, tasting and touching are your five senses.
Grade 1 Life Science: Animal Homes and Habits, Lesson 8.1 (grade 1) · Kindergarten Life Science: God Made the Animals, Lesson 6.3 (grade K)
setae (singular seta)English
Tiny stiff bristles on the underside and sides of most segments. Earthworms have four pairs per segment and use them to grip the soil while they crawl.
Grade 7 Life Science: Cells and Microbes, Lesson 8.1 (grade 7)
Tiny stiff bristles on the underside and sides of most segments. Earthworms have four pairs per segment and use them to grip the soil while they crawl.
Grade 7 Life Science: Cells and Microbes, Lesson 8.1 (grade 7)
settleEnglish
To sink slowly to the bottom of water and stay there.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.1 (grade K) · Grade 1 Engineering & Physics, Lesson 5.3 (grade 1)
To sink slowly to the bottom of water and stay there.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.1 (grade K) · Grade 1 Engineering & Physics, Lesson 5.3 (grade 1)
severe thunderstormEnglish
A thunderstorm that produces hail at least 2.5 cm across, wind gusts of at least 93 km/h, or a tornado.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.2 (grade 8)
A thunderstorm that produces hail at least 2.5 cm across, wind gusts of at least 93 km/h, or a tornado.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.2 (grade 8)
sex-linked traitEnglish
A trait whose gene lies on the X chromosome. Recessive sex-linked traits show up far more often in males, who have only one X.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.4 (grade 8)
A trait whose gene lies on the X chromosome. Recessive sex-linked traits show up far more often in males, who have only one X.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.4 (grade 8)
shadow clockEnglish
A stick standing in the sun whose shadow moves around it during the day, so you can tell the time. Another name is a sundial.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.4 (grade K)
A stick standing in the sun whose shadow moves around it during the day, so you can tell the time. Another name is a sundial.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.4 (grade K)
shadow zoneEnglish
A region on Earth’s surface, about 104° to 140° from an earthquake, where strong P waves do not arrive because the core bends them away.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.1 (grade 6)
A region on Earth’s surface, about 104° to 140° from an earthquake, where strong P waves do not arrive because the core bends them away.
Grade 6 Earth Science: The Dynamic Earth, Lesson 1.1 (grade 6)
shaftEnglish
The stiff stick down the middle of a feather. The bare end is called the quill.
Kindergarten Life Science: God Made the Animals, Lesson 3.1 (grade K)
The stiff stick down the middle of a feather. The bare end is called the quill.
Kindergarten Life Science: God Made the Animals, Lesson 3.1 (grade K)
shaft and aditEnglish
A shaft is a vertical opening down to underground workings; an adit is a nearly level tunnel driven into a hillside. Horizontal tunnels that follow the ore are called drifts.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.2 (grade 8)
A shaft is a vertical opening down to underground workings; an adit is a nearly level tunnel driven into a hillside. Horizontal tunnels that follow the ore are called drifts.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.2 (grade 8)
shake tableEnglish
A flat platform that slides back and forth to copy the shaking of an earthquake.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.2 (grade 2) · Grade 4 Engineering & Physics, Lesson 3.4 (grade 4)
A flat platform that slides back and forth to copy the shaking of an earthquake.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.2 (grade 2) · Grade 4 Engineering & Physics, Lesson 3.4 (grade 4)
shaleEnglish
Soft rock made of hardened mud. It breaks into thin flat pieces.
Grade 2 Earth Science: The Earth's Surface, Lesson 8.2 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.2 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.3 (grade 3) · +2 more
Soft rock made of hardened mud. It breaks into thin flat pieces.
Grade 2 Earth Science: The Earth's Surface, Lesson 8.2 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.2 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.3 (grade 3) · +2 more
sharkEnglish
A fish with gill slits, rough skin and a skeleton made of cartilage instead of bone.
Grade 2 Life Science: Animal Families, Lesson 5.2 (grade 2)
A fish with gill slits, rough skin and a skeleton made of cartilage instead of bone.
Grade 2 Life Science: Animal Families, Lesson 5.2 (grade 2)
shellEnglish
The hard outside covering that keeps a soft sea animal, like a clam or snail, safe.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.3 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 6.3 (grade 2) · Explore Animals, Stop 3.4 (Ages 7–9) · +3 more
The hard outside covering that keeps a soft sea animal, like a clam or snail, safe.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.3 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 6.3 (grade 2) · Explore Animals, Stop 3.4 (Ages 7–9) · +3 more
shelterEnglish
A safe place to wait out a storm. For lightning it is an enclosed building or a hard-topped car; for a tornado it is the lowest floor, in an inside room with no windows.
Grade 4 Earth Science: Weather and Water, Lesson 9.3 (grade 4) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.4 (grade K) · Explore Animals, Stop 5.10 (Ages 7–9) · +3 more
A safe place to wait out a storm. For lightning it is an enclosed building or a hard-topped car; for a tornado it is the lowest floor, in an inside room with no windows.
Grade 4 Earth Science: Weather and Water, Lesson 9.3 (grade 4) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.4 (grade K) · Explore Animals, Stop 5.10 (Ages 7–9) · +3 more
shelter in placeEnglish
To stay where you are, in the safest part of a building, until the danger passes.
Grade 4 Earth Science: Weather and Water, Lesson 4.4 (grade 4)
To stay where you are, in the safest part of a building, until the danger passes.
Grade 4 Earth Science: Weather and Water, Lesson 4.4 (grade 4)
shelterbeltEnglish
A row or several rows of trees planted across the wind to slow it and protect fields, farmsteads and livestock. Also called a windbreak.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.3 (grade 8) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 8.4 (grade 4)
A row or several rows of trees planted across the wind to slow it and protect fields, farmsteads and livestock. Also called a windbreak.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.3 (grade 8) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 8.4 (grade 4)
shepherdEnglish
A person who takes care of sheep and keeps them safe.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.4 (grade K) · Kindergarten Life Science: God Made the Animals, Lesson 1.3 (grade K) · Kindergarten Physical Education & Health, Lesson 4.1 (grade K) · +1 more
A person who takes care of sheep and keeps them safe.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.4 (grade K) · Kindergarten Life Science: God Made the Animals, Lesson 1.3 (grade K) · Kindergarten Physical Education & Health, Lesson 4.1 (grade K) · +1 more
SherpaEnglish
A people who live high in the mountains of Nepal. Many Sherpas are strong, skilled climbers and mountain guides.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.1 (grade 2) · Grade 5 Geography: Explorers, Navigators and Missionaries, Lesson 7.4 (grade 5)
A people who live high in the mountains of Nepal. Many Sherpas are strong, skilled climbers and mountain guides.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.1 (grade 2) · Grade 5 Geography: Explorers, Navigators and Missionaries, Lesson 7.4 (grade 5)
shieldEnglish
A large, stiff piece of armor. An armadillo has a shield over its shoulders and another over its hips.
Grade 3 Life Science: Plants and Animals Together, Lesson 6.3 (grade 3)
A large, stiff piece of armor. An armadillo has a shield over its shoulders and another over its hips.
Grade 3 Life Science: Plants and Animals Together, Lesson 6.3 (grade 3)
shield volcanoEnglish
A wide volcano with gently sloping sides, shaped like a warrior’s round shield lying on the ground. It is built by runny lava that flows far.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.4 (grade 2) · Grade 6 Earth Science: The Dynamic Earth, Lesson 3.3 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 3.2 (grade 6)
A wide volcano with gently sloping sides, shaped like a warrior’s round shield lying on the ground. It is built by runny lava that flows far.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.4 (grade 2) · Grade 6 Earth Science: The Dynamic Earth, Lesson 3.3 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 3.2 (grade 6)
shoalingEnglish
What happens as a wave enters shallow water: it slows down, its wavelength shrinks and its height grows.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.4 (grade 6)
What happens as a wave enters shallow water: it slows down, its wavelength shrinks and its height grows.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.4 (grade 6)
shoreEnglish
The edge of the land where it meets the sea.
Grade 2 Earth Science: The Earth's Surface, Lesson 6.4 (grade 2) · Grade 2 Earth Science: The Earth's Surface, Lesson 9.4 (grade 2)
The edge of the land where it meets the sea.
Grade 2 Earth Science: The Earth's Surface, Lesson 6.4 (grade 2) · Grade 2 Earth Science: The Earth's Surface, Lesson 9.4 (grade 2)
short-term memoryEnglish
The brain’s small “notepad” that holds a few things (about 7) for a short time, such as a phone number you are about to dial.
Grade 5 Life Science: The Human Body, Lesson 6.3 (grade 5)
The brain’s small “notepad” that holds a few things (about 7) for a short time, such as a phone number you are about to dial.
Grade 5 Life Science: The Human Body, Lesson 6.3 (grade 5)
sign stimulusEnglish
A simple, specific signal, such as a color, shape or sound, that sets off an instinctive behavior.
Grade 6 Life Science: Animal Design and Behavior, Lesson 5.4 (grade 6)
A simple, specific signal, such as a color, shape or sound, that sets off an instinctive behavior.
Grade 6 Life Science: Animal Design and Behavior, Lesson 5.4 (grade 6)
silicaEnglish
Silicon dioxide, the main ingredient of most magma. More silica makes magma stickier and more explosive.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.3 (grade 6)
Silicon dioxide, the main ingredient of most magma. More silica makes magma stickier and more explosive.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.3 (grade 6)
simple microscopeEnglish
A microscope with only one lens. Leeuwenhoek’s instruments were simple microscopes with a single, tiny, very curved lens.
Grade 7 Life Science: Cells and Microbes, Lesson 1.1 (grade 7)
A microscope with only one lens. Leeuwenhoek’s instruments were simple microscopes with a single, tiny, very curved lens.
Grade 7 Life Science: Cells and Microbes, Lesson 1.1 (grade 7)
sinkEnglish
To go down to the bottom of the water.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 3.3 (grade K) · Grade 1 Engineering & Physics, Lesson 6.1 (grade 1) · Grade 2 Engineering & Physics, Lesson 3.1 (grade 2) · +3 more
To go down to the bottom of the water.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 3.3 (grade K) · Grade 1 Engineering & Physics, Lesson 6.1 (grade 1) · Grade 2 Engineering & Physics, Lesson 3.1 (grade 2) · +3 more
six-sidedEnglish
Having six sides or six arms, like almost every snowflake.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 8.3 (grade 1)
Having six sides or six arms, like almost every snowflake.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 8.3 (grade 1)
sizeEnglish
How big something is: how tall, how long or how heavy.
Kindergarten Life Science: God Made the Animals, Lesson 8.2 (grade K)
How big something is: how tall, how long or how heavy.
Kindergarten Life Science: God Made the Animals, Lesson 8.2 (grade K)
skeletal muscleEnglish
Muscle attached to bones by tendons; you can move it when you choose.
Grade 5 Life Science: The Human Body, Lesson 2.4 (grade 5)
Muscle attached to bones by tendons; you can move it when you choose.
Grade 5 Life Science: The Human Body, Lesson 2.4 (grade 5)
skinEnglish
The soft cover over your whole body. It keeps you safe and feels what touches you.
Grade 1 Life Science: Animal Homes and Habits, Lesson 8.4 (grade 1) · Grade 5 Life Science: The Human Body, Lesson 7.4 (grade 5)
The soft cover over your whole body. It keeps you safe and feels what touches you.
Grade 1 Life Science: Animal Homes and Habits, Lesson 8.4 (grade 1) · Grade 5 Life Science: The Human Body, Lesson 7.4 (grade 5)
slateEnglish
A hard, fine-grained metamorphic rock that splits into thin, smooth, flat sheets. Its parent rock is shale.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.3 (grade 3)
A hard, fine-grained metamorphic rock that splits into thin, smooth, flat sheets. Its parent rock is shale.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.3 (grade 3)
sledEnglish
A low cart with long runners that slides over snow and ice, often pulled by dogs.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.4 (grade 2) · Grade 1 Engineering & Physics, Lesson 3.3 (grade 1)
A low cart with long runners that slides over snow and ice, often pulled by dogs.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.4 (grade 2) · Grade 1 Engineering & Physics, Lesson 3.3 (grade 1)
sleep cycleEnglish
One trip through the stages of sleep, from light sleep to deep sleep to REM sleep. A cycle lasts about 90 minutes, and a night has several.
Grade 5 Life Science: The Human Body, Lesson 6.4 (grade 5)
One trip through the stages of sleep, from light sleep to deep sleep to REM sleep. A cycle lasts about 90 minutes, and a night has several.
Grade 5 Life Science: The Human Body, Lesson 6.4 (grade 5)
slumpEnglish
A block of soil or soft rock that slides down a curved surface and tilts backward as it goes, leaving a crescent-shaped scar at the top.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.3 (grade 6)
A block of soil or soft rock that slides down a curved surface and tilts backward as it goes, leaving a crescent-shaped scar at the top.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.3 (grade 6)
small intestineEnglish
The long, coiled tube after the stomach, about 6 to 7 meters (20 to 23 feet) long, where most digestion finishes and food passes into the blood.
Grade 5 Life Science: The Human Body, Lesson 5.3 (grade 5)
The long, coiled tube after the stomach, about 6 to 7 meters (20 to 23 feet) long, where most digestion finishes and food passes into the blood.
Grade 5 Life Science: The Human Body, Lesson 5.3 (grade 5)
smallpoxEnglish
A dangerous disease that spread from person to person and caused fever and blisters all over the body. About 3 out of every 10 people who caught it died, and many who lived were left with scars.
Grade 5 Life Science: The Human Body, Lesson 8.1 (grade 5)
A dangerous disease that spread from person to person and caused fever and blisters all over the body. About 3 out of every 10 people who caught it died, and many who lived were left with scars.
Grade 5 Life Science: The Human Body, Lesson 8.1 (grade 5)
smeltingEnglish
Heating crushed ore very hot in a furnace so the metal melts free from the rock.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.2 (grade 3)
Heating crushed ore very hot in a furnace so the metal melts free from the rock.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.2 (grade 3)
snowEnglish
Soft flakes of ice that fall from the clouds when the air is very cold.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.1 (grade K)
Soft flakes of ice that fall from the clouds when the air is very cold.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.1 (grade K)
snow lineEnglish
The height on a mountain above which snow stays on the ground all year long.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.4 (grade 2)
The height on a mountain above which snow stays on the ground all year long.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.4 (grade 2)
snowcapEnglish
Snow and ice that cover the top of a high mountain, often all year long.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.3 (grade 2) · Grade 1 Geography: Maps and Journeys, Lesson 5.4 (grade 1)
Snow and ice that cover the top of a high mountain, often all year long.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.3 (grade 2) · Grade 1 Geography: Maps and Journeys, Lesson 5.4 (grade 1)
snowdriftEnglish
A deep pile of snow heaped up by the wind.
Grade 4 Earth Science: Weather and Water, Lesson 4.3 (grade 4)
A deep pile of snow heaped up by the wind.
Grade 4 Earth Science: Weather and Water, Lesson 4.3 (grade 4)
snowflakeEnglish
A tiny piece of ice that grows in a cloud and falls to the ground as snow.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 8.3 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.4 (grade K)
A tiny piece of ice that grows in a cloud and falls to the ground as snow.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 8.3 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.4 (grade K)
soak inEnglish
When water sinks down into dirt, the way a sponge drinks up water.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 3.2 (grade K)
When water sinks down into dirt, the way a sponge drinks up water.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 3.2 (grade K)
sodEnglish
The top layer of a grassland, where living and dead grass roots knit the soil into a tough mat that wind and rain cannot easily break.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.1 (grade 8) · Grade 1 Geography: Maps and Journeys, Lesson 3.2 (grade 1) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 3.4 (grade 4) · +1 more
The top layer of a grassland, where living and dead grass roots knit the soil into a tough mat that wind and rain cannot easily break.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.1 (grade 8) · Grade 1 Geography: Maps and Journeys, Lesson 3.2 (grade 1) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 3.4 (grade 4) · +1 more
softEnglish
Easy to scratch, dent or rub away. A soft rock gets a groove or makes powder when you scratch it.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.2 (grade K)
Easy to scratch, dent or rub away. A soft rock gets a groove or makes powder when you scratch it.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.2 (grade K)
soft tissueEnglish
The soft parts of a body, such as skin, muscle, blood vessels and cells, not the hard bone or teeth.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.4 (grade 3) · Explore Dinosaurs · Ranger, Stop 2.10 (Ages 10–13) · Explore Dinosaurs, Stop 2.10 (Ages 7–9) · +1 more
The soft parts of a body, such as skin, muscle, blood vessels and cells, not the hard bone or teeth.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.4 (grade 3) · Explore Dinosaurs · Ranger, Stop 2.10 (Ages 10–13) · Explore Dinosaurs, Stop 2.10 (Ages 7–9) · +1 more
soft-sediment deformationEnglish
Bending or folding of layers that happened while they were still wet and unhardened, before they turned to stone.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.2 (grade 6)
Bending or folding of layers that happened while they were still wet and unhardened, before they turned to stone.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.2 (grade 6)
soilEnglish
The loose top layer of the ground where plants grow. It is made of sand, silt, clay, old bits of plants, air and water.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 2.3 (grade 1) · Grade 6 Earth Science: The Dynamic Earth, Lesson 9.2 (grade 6) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.1 (grade K) · +3 more
The loose top layer of the ground where plants grow. It is made of sand, silt, clay, old bits of plants, air and water.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 2.3 (grade 1) · Grade 6 Earth Science: The Dynamic Earth, Lesson 9.2 (grade 6) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.1 (grade K) · +3 more
Soil Conservation ServiceEnglish
The United States agency created by the Soil Conservation Act of April 27, 1935, to help farmers stop erosion. Since 1994 it has been called the Natural Resources Conservation Service (NRCS).
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.1 (grade 8)
The United States agency created by the Soil Conservation Act of April 27, 1935, to help farmers stop erosion. Since 1994 it has been called the Natural Resources Conservation Service (NRCS).
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.1 (grade 8)
soil map unitEnglish
An area on a soil map labeled with a short symbol that stands for a named soil series and its slope, such as a silt loam on 2 to 6 percent slopes.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.1 (grade 8)
An area on a soil map labeled with a short symbol that stands for a named soil series and its slope, such as a silt loam on 2 to 6 percent slopes.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.1 (grade 8)
soil profileEnglish
A vertical slice of soil from the surface down to bedrock, showing its layers.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.2 (grade 8) · Grade 4 Gardening & Animals, Lesson 3.1 (grade 4)
A vertical slice of soil from the surface down to bedrock, showing its layers.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.2 (grade 8) · Grade 4 Gardening & Animals, Lesson 3.1 (grade 4)
soil sampleEnglish
Soil collected for testing: usually 10 to 15 small cores taken 15 cm deep across a field, mixed together, dried and sent to a laboratory.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.4 (grade 8) · Grade 6 Gardening & Animals, Lesson 3.4 (grade 6)
Soil collected for testing: usually 10 to 15 small cores taken 15 cm deep across a field, mixed together, dried and sent to a laboratory.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.4 (grade 8) · Grade 6 Gardening & Animals, Lesson 3.4 (grade 6)
soil surveyEnglish
A careful, systematic study that samples soil at many points and draws a map showing where each kind of soil lies.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.1 (grade 8)
A careful, systematic study that samples soil at many points and draws a map showing where each kind of soil lies.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.1 (grade 8)
soil textureEnglish
The proportions of sand, silt and clay in a soil, estimated from the layers that settle in a jar of shaken soil and water.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.2 (grade 8) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.1 (grade 8) · Grade 5 Gardening & Animals, Lesson 3.1 (grade 5) · +2 more
The proportions of sand, silt and clay in a soil, estimated from the layers that settle in a jar of shaken soil and water.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.2 (grade 8) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.1 (grade 8) · Grade 5 Gardening & Animals, Lesson 3.1 (grade 5) · +2 more
solar eclipseEnglish
When the Moon passes between the Sun and Earth and its shadow falls on Earth, hiding all or part of the Sun. It can happen only at new moon.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.3 (grade 5)
When the Moon passes between the Sun and Earth and its shadow falls on Earth, hiding all or part of the Sun. It can happen only at new moon.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.3 (grade 5)
solar noonEnglish
The moment each day when the sun is highest in the sky and shadows are shortest. In most of the United States the sun is then due south and shadows point due north.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.2 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.1 (grade 5)
The moment each day when the sun is highest in the sky and shadows are shortest. In most of the United States the sun is then due south and shadows point due north.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.2 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.1 (grade 5)
solar systemEnglish
The Sun and everything that travels around it: eight planets, their moons, dwarf planets, asteroids and comets.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.1 (grade 5)
The Sun and everything that travels around it: eight planets, their moons, dwarf planets, asteroids and comets.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.1 (grade 5)
solar yearEnglish
The time from one spring equinox to the next, about 365 days, 5 hours and 49 minutes (about 365.2422 days). The seasons repeat on this schedule.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.3 (grade 5)
The time from one spring equinox to the next, about 365 days, 5 hours and 49 minutes (about 365.2422 days). The seasons repeat on this schedule.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.3 (grade 5)
solid groundEnglish
Hard ground, like rock, that stays firm when it is shaken.
Grade 2 Earth Science: The Earth's Surface, Lesson 9.3 (grade 2)
Hard ground, like rock, that stays firm when it is shaken.
Grade 2 Earth Science: The Earth's Surface, Lesson 9.3 (grade 2)
solsticeEnglish
One of the two days each year when the noon Sun is highest or lowest in the sky: about June 21 and December 21. From Latin words meaning “the sun stands still.”
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.2 (grade 5) · Grade 3 Gardening & Animals, Lesson 1.2 (grade 3) · Grade 5 Gardening & Animals, Lesson 1.1 (grade 5) · +2 more
One of the two days each year when the noon Sun is highest or lowest in the sky: about June 21 and December 21. From Latin words meaning “the sun stands still.”
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.2 (grade 5) · Grade 3 Gardening & Animals, Lesson 1.2 (grade 3) · Grade 5 Gardening & Animals, Lesson 1.1 (grade 5) · +2 more
sortEnglish
To put things that are alike into the same group.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.1 (grade K) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.1 (grade K) · Kindergarten Engineering & Physics, Lesson 4.2 (grade K) · +3 more
To put things that are alike into the same group.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.1 (grade K) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.1 (grade K) · Kindergarten Engineering & Physics, Lesson 4.2 (grade K) · +3 more
sortingEnglish
The separating of grains by size as water slows. Coarse grains settle first, fine grains last, so each place on a delta gets its own grain size.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.2 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 2.3 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 9.3 (grade 7)
The separating of grains by size as water slows. Coarse grains settle first, fine grains last, so each place on a delta gets its own grain size.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.2 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 2.3 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 9.3 (grade 7)
sorus (plural sori)English
A small cluster of spore cases, seen as a brown or orange dot on the underside of a fern frond.
Grade 4 Life Science: Classification, Lesson 6.1 (grade 4)
A small cluster of spore cases, seen as a brown or orange dot on the underside of a fern frond.
Grade 4 Life Science: Classification, Lesson 6.1 (grade 4)
source rockEnglish
A dark, organic-rich rock, usually shale, from which oil and natural gas were generated by heat and pressure.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.3 (grade 8)
A dark, organic-rich rock, usually shale, from which oil and natural gas were generated by heat and pressure.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.3 (grade 8)
south celestial poleEnglish
The point in the sky right above the earth’s South Pole. Southern stars circle around it, but no bright star marks it.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.3 (grade 5)
The point in the sky right above the earth’s South Pole. Southern stars circle around it, but no bright star marks it.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.3 (grade 5)
Southern CrossEnglish
Crux, a small, bright constellation of four main stars shaped like a cross. It is used to find south in the Southern Hemisphere.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.3 (grade 5)
Crux, a small, bright constellation of four main stars shaped like a cross. It is used to find south in the Southern Hemisphere.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.3 (grade 5)
Southern HemisphereEnglish
The half of the earth south of the equator.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.3 (grade 5)
The half of the earth south of the equator.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.3 (grade 5)
space probeEnglish
A robot spacecraft with no people aboard, sent to explore space and send back pictures and measurements by radio.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.4 (grade 5)
A robot spacecraft with no people aboard, sent to explore space and send back pictures and measurements by radio.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.4 (grade 5)
space telescopeEnglish
A telescope that works above the earth’s air, where the air cannot blur or block the light.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.2 (grade 5)
A telescope that works above the earth’s air, where the air cannot blur or block the light.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.2 (grade 5)
spaced practiceEnglish
Reviewing something several times with breaks of hours or days in between, instead of all at once.
Grade 5 Life Science: The Human Body, Lesson 6.3 (grade 5)
Reviewing something several times with breaks of hours or days in between, instead of all at once.
Grade 5 Life Science: The Human Body, Lesson 6.3 (grade 5)
spanEnglish
An old Bible measure: the width of a grown man’s hand stretched wide, from thumb tip to little-finger tip. It is about 9 inches (about 23 centimeters).
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.1 (grade 3) · Architecture & Civil Engineering, Lesson 6.1 (grade 9–12) · Grade 1 Engineering & Physics, Lesson 2.2 (grade 1) · +3 more
An old Bible measure: the width of a grown man’s hand stretched wide, from thumb tip to little-finger tip. It is about 9 inches (about 23 centimeters).
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.1 (grade 3) · Architecture & Civil Engineering, Lesson 6.1 (grade 9–12) · Grade 1 Engineering & Physics, Lesson 2.2 (grade 1) · +3 more
spatulaeEnglish
The hundreds of tiny flat tips at the end of each seta, about 0.2 µm (200 nm) wide. They are the parts that touch the wall.
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.3 (grade 6)
The hundreds of tiny flat tips at the end of each seta, about 0.2 µm (200 nm) wide. They are the parts that touch the wall.
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.3 (grade 6)
specialized cellEnglish
A cell with a special shape and parts that suit it for one job, such as a nerve cell or a red blood cell.
Grade 5 Life Science: The Human Body, Lesson 1.4 (grade 5)
A cell with a special shape and parts that suit it for one job, such as a nerve cell or a red blood cell.
Grade 5 Life Science: The Human Body, Lesson 1.4 (grade 5)
speciesEnglish
The smallest common group in classification, given a two-part Latin name such as Triceratops horridus. For fossils, a species is a judgment made from bones.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.1 (grade 7) · Explore Animals · Ranger, Stop 1.7 (Ages 10–13) · Explore Animals · Ranger, Stop 2.10 (Ages 10–13) · +3 more
The smallest common group in classification, given a two-part Latin name such as Triceratops horridus. For fossils, a species is a judgment made from bones.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.1 (grade 7) · Explore Animals · Ranger, Stop 1.7 (Ages 10–13) · Explore Animals · Ranger, Stop 2.10 (Ages 10–13) · +3 more
species pageEnglish
One page of a field guide that tells everything a reader needs to name and understand one species.
Grade 4 Life Science: Classification, Lesson 8.3 (grade 4)
One page of a field guide that tells everything a reader needs to name and understand one species.
Grade 4 Life Science: Classification, Lesson 8.3 (grade 4)
species richnessEnglish
The number of different kinds of living things found in an area.
Grade 7 Life Science: Cells and Microbes, Lesson 9.2 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 9.2 (grade 8)
The number of different kinds of living things found in an area.
Grade 7 Life Science: Cells and Microbes, Lesson 9.2 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 9.2 (grade 8)
species wordEnglish
The second part of a scientific name. It is written in small letters and often describes the living thing, such as alba (white) or borealis (northern).
Grade 4 Life Science: Classification, Lesson 1.3 (grade 4)
The second part of a scientific name. It is written in small letters and often describes the living thing, such as alba (white) or borealis (northern).
Grade 4 Life Science: Classification, Lesson 1.3 (grade 4)
specified complexityEnglish
William Dembski’s term for something that is both highly improbable (complex) and matches an independent, meaningful pattern (specified), such as a written sentence.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.3 (grade 8)
William Dembski’s term for something that is both highly improbable (complex) and matches an independent, meaningful pattern (specified), such as a written sentence.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.3 (grade 8)
specimen numberEnglish
A number written on a specimen and on its label and notebook page, so the three always match.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 8.1 (grade 3)
A number written on a specimen and on its label and notebook page, so the three always match.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 8.1 (grade 3)
spectral classEnglish
A star’s type, named by a letter: O, B, A, F, G, K or M, in order from hottest to coolest. The Sun is a G star.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.3 (grade 5)
A star’s type, named by a letter: O, B, A, F, G, K or M, in order from hottest to coolest. The Sun is a G star.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.3 (grade 5)
spectrumEnglish
The band of colors made when light is spread out: red, orange, yellow, green, blue and violet. Star spectra also show thin dark lines.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.3 (grade 5)
The band of colors made when light is spread out: red, orange, yellow, green, blue and violet. Star spectra also show thin dark lines.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.3 (grade 5)
speed of lightEnglish
How fast light travels: about 300,000 kilometers (186,000 miles) every second in empty space.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.4 (grade 5)
How fast light travels: about 300,000 kilometers (186,000 miles) every second in empty space.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.4 (grade 5)
speleothemEnglish
Any mineral deposit formed in a cave from dripping or flowing water, including stalactites, stalagmites, columns, flowstone, soda straws, and helictites.
High School Geology, Lesson 4.2 (grade 9–12)
Any mineral deposit formed in a cave from dripping or flowing water, including stalactites, stalagmites, columns, flowstone, soda straws, and helictites.
High School Geology, Lesson 4.2 (grade 9–12)
spillwayEnglish
A channel that lets extra water flow safely around or over a dam so the water does not pour over the top of the dam itself.
Grade 4 Earth Science: Weather and Water, Lesson 6.1 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 8.2 (grade 6) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 6.3 (grade 8)
A channel that lets extra water flow safely around or over a dam so the water does not pour over the top of the dam itself.
Grade 4 Earth Science: Weather and Water, Lesson 6.1 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 8.2 (grade 6) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 6.3 (grade 8)
spinal cordEnglish
A thick bundle of nerves that runs through a tunnel inside the vertebrae and carries messages between the brain and the body.
Grade 4 Life Science: Classification, Lesson 2.2 (grade 4) · Grade 5 Life Science: The Human Body, Lesson 6.1 (grade 5)
A thick bundle of nerves that runs through a tunnel inside the vertebrae and carries messages between the brain and the body.
Grade 4 Life Science: Classification, Lesson 2.2 (grade 4) · Grade 5 Life Science: The Human Body, Lesson 6.1 (grade 5)
spiraclesEnglish
Small openings along the sides of an insect’s thorax and abdomen that let air into the tracheal tubes. Many can open and close like valves.
Grade 7 Life Science: Cells and Microbes, Lesson 7.3 (grade 7)
Small openings along the sides of an insect’s thorax and abdomen that let air into the tracheal tubes. Many can open and close like valves.
Grade 7 Life Science: Cells and Microbes, Lesson 7.3 (grade 7)
spirometerEnglish
An instrument that measures how much air a person breathes out. The name comes from the Latin word spirare, “to breathe.”
Grade 5 Life Science: The Human Body, Lesson 4.2 (grade 5)
An instrument that measures how much air a person breathes out. The name comes from the Latin word spirare, “to breathe.”
Grade 5 Life Science: The Human Body, Lesson 4.2 (grade 5)
splash erosionEnglish
The knocking loose of soil grains by the impact of raindrops. It is the first step of water erosion.
Grade 6 Earth Science: The Dynamic Earth, Lesson 9.1 (grade 6)
The knocking loose of soil grains by the impact of raindrops. It is the first step of water erosion.
Grade 6 Earth Science: The Dynamic Earth, Lesson 9.1 (grade 6)
splitterEnglish
A skilled quarry worker who splits blocks of slate into thin sheets with a chisel and mallet.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.3 (grade 3)
A skilled quarry worker who splits blocks of slate into thin sheets with a chisel and mallet.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.3 (grade 3)
spongy boneEnglish
The lighter inner layer of bone, built like a honeycomb of tiny struts, found especially at the ends of long bones.
Grade 5 Life Science: The Human Body, Lesson 2.2 (grade 5)
The lighter inner layer of bone, built like a honeycomb of tiny struts, found especially at the ends of long bones.
Grade 5 Life Science: The Human Body, Lesson 2.2 (grade 5)
sporangium (plural sporangia)English
A round case at the tip of an upright hypha that fills with spores and breaks open to release them, as in black bread mold.
Grade 7 Life Science: Cells and Microbes, Lesson 6.2 (grade 7)
A round case at the tip of an upright hypha that fills with spores and breaks open to release them, as in black bread mold.
Grade 7 Life Science: Cells and Microbes, Lesson 6.2 (grade 7)
spore printEnglish
The pattern of spores that falls from a mushroom cap onto paper placed under it. Its color is an important clue for identifying a mushroom.
Grade 7 Life Science: Cells and Microbes, Lesson 6.3 (grade 7)
The pattern of spores that falls from a mushroom cap onto paper placed under it. Its color is an important clue for identifying a mushroom.
Grade 7 Life Science: Cells and Microbes, Lesson 6.3 (grade 7)
springEnglish
A place where the water table meets the land surface and groundwater flows out on its own.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.1 (grade 8) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.1 (grade K) · Grade 1 Engineering & Physics, Lesson 9.4 (grade 1) · +3 more
A place where the water table meets the land surface and groundwater flows out on its own.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.1 (grade 8) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.1 (grade K) · Grade 1 Engineering & Physics, Lesson 9.4 (grade 1) · +3 more
spring tideEnglish
An extra-large tide range that comes near new moon and full moon, when the Sun and Moon pull in a line. It has nothing to do with the season of spring.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.4 (grade 5) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 7.3 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 8.1 (grade 6)
An extra-large tide range that comes near new moon and full moon, when the Sun and Moon pull in a line. It has nothing to do with the season of spring.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.4 (grade 5) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 7.3 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 8.1 (grade 6)
sproutEnglish
When a seed wakes up and its first root and shoot start to grow.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.4 (grade K) · Kindergarten Gardening & Animals, Lesson 5.2 (grade K) · Grade 2 Life Science: Animal Families, Lesson 8.4 (grade 2) · +1 more
When a seed wakes up and its first root and shoot start to grow.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.4 (grade K) · Kindergarten Gardening & Animals, Lesson 5.2 (grade K) · Grade 2 Life Science: Animal Families, Lesson 8.4 (grade 2) · +1 more
stadionEnglish
A Greek unit of length used by Eratosthenes (plural: stadia). Its exact length is not known for certain.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.1 (grade 5) · Sports & Games of the World, Lesson 3.1 (grade 4–7) · Sports & Games of the World, Lesson 1.3 (grade 8–12) · +1 more
A Greek unit of length used by Eratosthenes (plural: stadia). Its exact length is not known for certain.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.1 (grade 5) · Sports & Games of the World, Lesson 3.1 (grade 4–7) · Sports & Games of the World, Lesson 1.3 (grade 8–12) · +1 more
stainEnglish
A dye, such as iodine or methylene blue, that colors some parts of a cell more than others so they are easier to see.
Grade 5 Life Science: The Human Body, Lesson 1.2 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 1.3 (grade 7)
A dye, such as iodine or methylene blue, that colors some parts of a cell more than others so they are easier to see.
Grade 5 Life Science: The Human Body, Lesson 1.2 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 1.3 (grade 7)
stalactiteEnglish
A stone icicle that hangs down from a cave ceiling. It holds “tight” to the ceiling.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.2 (grade 2)
A stone icicle that hangs down from a cave ceiling. It holds “tight” to the ceiling.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.2 (grade 2)
stalagmiteEnglish
A stone bump that grows up from a cave floor, under a drip. It “might” reach the ceiling one day.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.2 (grade 2) · High School Geology, Lesson 4.2 (grade 9–12)
A stone bump that grows up from a cave floor, under a drip. It “might” reach the ceiling one day.
Grade 2 Earth Science: The Earth's Surface, Lesson 4.2 (grade 2) · High School Geology, Lesson 4.2 (grade 9–12)
standard timeEnglish
One agreed clock time used by everyone across a wide area, even though solar noon comes at slightly different moments across it.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.4 (grade 5) · Explore Travel and Faraway Places · Expert, Stop 1.5 (Ages 14+) · Explore Travel and Faraway Places · Ranger, Stop 1.5 (Ages 10–13) · +3 more
One agreed clock time used by everyone across a wide area, even though solar noon comes at slightly different moments across it.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.4 (grade 5) · Explore Travel and Faraway Places · Expert, Stop 1.5 (Ages 14+) · Explore Travel and Faraway Places · Ranger, Stop 1.5 (Ages 10–13) · +3 more
starEnglish
A huge, hot ball of glowing gas that makes its own light. The Sun is our nearest star.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.1 (grade 5) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 5.3 (grade K)
A huge, hot ball of glowing gas that makes its own light. The Sun is our nearest star.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.1 (grade 5) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 5.3 (grade K)
star catalogEnglish
A careful list of stars that gives each star’s place in the sky and how bright it looks.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.1 (grade 5)
A careful list of stars that gives each star’s place in the sky and how bright it looks.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.1 (grade 5)
star clusterEnglish
A family of stars that really are close together in space and move together, such as the Pleiades.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.2 (grade 5)
A family of stars that really are close together in space and move together, such as the Pleiades.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.2 (grade 5)
star compassEnglish
Using the pattern of stars that turn around the fixed point of the North Star (in the Northern Hemisphere) to find north at night.
Grade 6 Life Science: Animal Design and Behavior, Lesson 2.3 (grade 6)
Using the pattern of stars that turn around the fixed point of the North Star (in the Northern Hemisphere) to find north at night.
Grade 6 Life Science: Animal Design and Behavior, Lesson 2.3 (grade 6)
star mapEnglish
A drawing of the stars as they appear in the sky, showing their patterns and the angles between them.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.2 (grade 5)
A drawing of the stars as they appear in the sky, showing their patterns and the angles between them.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.2 (grade 5)
star patternEnglish
A group of stars that seem to make a picture in the sky when we connect them like dot-to-dot.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 5.4 (grade K)
A group of stars that seem to make a picture in the sky when we connect them like dot-to-dot.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 5.4 (grade K)
static water levelEnglish
The depth from the ground surface down to the water in a well when the pump has been off long enough for the water to settle.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.2 (grade 8)
The depth from the ground surface down to the water in a well when the pump has been off long enough for the water to settle.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.2 (grade 8)
stationary frontEnglish
A front that is hardly moving. Map symbol: a line of red half circles and blue triangles on opposite sides.
Grade 4 Earth Science: Weather and Water, Lesson 5.3 (grade 4)
A front that is hardly moving. Map symbol: a line of red half circles and blue triangles on opposite sides.
Grade 4 Earth Science: Weather and Water, Lesson 5.3 (grade 4)
StegosaurusEnglish
A plant-eating dinosaur with tall plates on its back and spikes on its tail.
Kindergarten Life Science: God Made the Animals, Lesson 7.2 (grade K)
A plant-eating dinosaur with tall plates on its back and spikes on its tail.
Kindergarten Life Science: God Made the Animals, Lesson 7.2 (grade K)
step lengthEnglish
The distance covered by one ordinary walking step, measured heel to heel. It lets you measure distance with your own body.
Grade 5 Life Science: The Human Body, Lesson 9.1 (grade 5)
The distance covered by one ordinary walking step, measured heel to heel. It lets you measure distance with your own body.
Grade 5 Life Science: The Human Body, Lesson 9.1 (grade 5)
sterileEnglish
Completely free of living microbes and their spores.
Grade 7 Life Science: Cells and Microbes, Lesson 3.4 (grade 7)
Completely free of living microbes and their spores.
Grade 7 Life Science: Cells and Microbes, Lesson 3.4 (grade 7)
sterilizeEnglish
To kill every living microbe on something, for example by heating surgical tools in steam under pressure.
Grade 5 Life Science: The Human Body, Lesson 8.3 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 4.2 (grade 7)
To kill every living microbe on something, for example by heating surgical tools in steam under pressure.
Grade 5 Life Science: The Human Body, Lesson 8.3 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 4.2 (grade 7)
stigmaEnglish
The sticky top of a flower’s pistil, where pollen must land for seeds to form.
Grade 3 Life Science: Plants and Animals Together, Lesson 3.4 (grade 3)
The sticky top of a flower’s pistil, where pollen must land for seeds to form.
Grade 3 Life Science: Plants and Animals Together, Lesson 3.4 (grade 3)
stiltsEnglish
Strong posts or piers that hold a building up off the ground so water can flow underneath.
Grade 4 Earth Science: Weather and Water, Lesson 6.4 (grade 4) · Sports & Games of the World, Lesson 1.3 (grade 4–7)
Strong posts or piers that hold a building up off the ground so water can flow underneath.
Grade 4 Earth Science: Weather and Water, Lesson 6.4 (grade 4) · Sports & Games of the World, Lesson 1.3 (grade 4–7)
stimulusEnglish
Something in the surroundings that an animal senses and responds to, such as a sound, a smell, a shape or a touch. The plural is stimuli.
Grade 6 Life Science: Animal Design and Behavior, Lesson 5.1 (grade 6)
Something in the surroundings that an animal senses and responds to, such as a sound, a smell, a shape or a touch. The plural is stimuli.
Grade 6 Life Science: Animal Design and Behavior, Lesson 5.1 (grade 6)
stocksEnglish
Heavy wooden boards with holes that held a prisoner’s feet tight so he could not move.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.4 (grade 2)
Heavy wooden boards with holes that held a prisoner’s feet tight so he could not move.
Grade 2 Earth Science: The Earth's Surface, Lesson 3.4 (grade 2)
stomachEnglish
A stretchy, muscular bag under the left ribs that stores food, churns it and mixes it with gastric juice.
Grade 5 Life Science: The Human Body, Lesson 5.1 (grade 5)
A stretchy, muscular bag under the left ribs that stores food, churns it and mixes it with gastric juice.
Grade 5 Life Science: The Human Body, Lesson 5.1 (grade 5)
stomach contentsEnglish
Food found inside the belly of a fossil animal, showing what it ate last.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.3 (grade 3)
Food found inside the belly of a fossil animal, showing what it ate last.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.3 (grade 3)
stormEnglish
Very strong wind, often with rain, that can make big waves on the water.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.4 (grade 1)
Very strong wind, often with rain, that can make big waves on the water.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.4 (grade 1)
storm drainEnglish
A grate or opening in the street or curb where rainwater goes down into a pipe.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.2 (grade 1)
A grate or opening in the street or curb where rainwater goes down into a pipe.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.2 (grade 1)
storm spotterEnglish
A trained volunteer who watches a storm in person and reports what the radar cannot see, such as a funnel reaching the ground. Spotters are not chasers; they report from a safe place.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.2 (grade 8)
A trained volunteer who watches a storm in person and reports what the radar cannot see, such as a funnel reaching the ground. Spotters are not chasers; they report from a safe place.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.2 (grade 8)
storm surgeEnglish
A dome of seawater pushed onto the shore by a storm’s winds, raising the sea far above its normal level.
Grade 4 Earth Science: Weather and Water, Lesson 4.1 (grade 4) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 2.4 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 8.1 (grade 6) · +2 more
A dome of seawater pushed onto the shore by a storm’s winds, raising the sea far above its normal level.
Grade 4 Earth Science: Weather and Water, Lesson 4.1 (grade 4) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 2.4 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 8.1 (grade 6) · +2 more
storm warningEnglish
A message sent ahead of a storm so people can get ready and stay safe.
Grade 4 Earth Science: Weather and Water, Lesson 5.2 (grade 4)
A message sent ahead of a storm so people can get ready and stay safe.
Grade 4 Earth Science: Weather and Water, Lesson 5.2 (grade 4)
strain rateEnglish
How fast a material is being bent or stretched. The same material may bend when pushed slowly and snap when pushed fast.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.2 (grade 6)
How fast a material is being bent or stretched. The same material may bend when pushed slowly and snap when pushed fast.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.2 (grade 6)
strataEnglish
Layers of sedimentary rock, one on top of another. One layer is a stratum.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.1 (grade 7) · Explore Travel and Faraway Places · Expert, Stop 4.8 (Ages 14+) · Explore Travel and Faraway Places · Ranger, Stop 4.8 (Ages 10–13)
Layers of sedimentary rock, one on top of another. One layer is a stratum.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.1 (grade 7) · Explore Travel and Faraway Places · Expert, Stop 4.8 (Ages 14+) · Explore Travel and Faraway Places · Ranger, Stop 4.8 (Ages 10–13)
stratigraphic columnEnglish
A drawing of the beds at one place stacked in order from oldest at the bottom to youngest at the top, drawn to a vertical scale.
Grade 7 Earth Science: Earth History and the Flood, Lesson 9.2 (grade 7)
A drawing of the beds at one place stacked in order from oldest at the bottom to youngest at the top, drawn to a vertical scale.
Grade 7 Earth Science: Earth History and the Flood, Lesson 9.2 (grade 7)
stratigraphic sectionEnglish
A measured record of layers from bottom to top, drawn as a column at a fixed scale.
High School Geology, Lesson 9.2 (grade 9–12)
A measured record of layers from bottom to top, drawn as a column at a fixed scale.
High School Geology, Lesson 9.2 (grade 9–12)
stratumEnglish
One layer of rock. More than one layer are called strata.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.4 (grade 3)
One layer of rock. More than one layer are called strata.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.4 (grade 3)
stratum (plural strata)English
One layer of rock or sediment. Many layers together are called strata.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.1 (grade 3) · Grade 6 Earth Science: The Dynamic Earth, Lesson 9.4 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 1.1 (grade 7) · +1 more
One layer of rock or sediment. Many layers together are called strata.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.1 (grade 3) · Grade 6 Earth Science: The Dynamic Earth, Lesson 9.4 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 1.1 (grade 7) · +1 more
stratusEnglish
A flat, gray cloud that spreads across the sky like a blanket. The name means “spread out.”
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 4.1 (grade 1) · Grade 4 Earth Science: Weather and Water, Lesson 3.1 (grade 4) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.3 (grade K)
A flat, gray cloud that spreads across the sky like a blanket. The name means “spread out.”
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 4.1 (grade 1) · Grade 4 Earth Science: Weather and Water, Lesson 3.1 (grade 4) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 9.3 (grade K)
strawEnglish
The dry, hollow stems of grain plants like wheat. Brick makers mix it into mud to make bricks stronger.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.3 (grade K)
The dry, hollow stems of grain plants like wheat. Brick makers mix it into mud to make bricks stronger.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.3 (grade K)
streakEnglish
The color of a mineral’s powder, made by rubbing the mineral across a rough white tile.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.2 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.2 (grade 3) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.1 (grade 8) · +3 more
The color of a mineral’s powder, made by rubbing the mineral across a rough white tile.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.2 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.2 (grade 3) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.1 (grade 8) · +3 more
streak plateEnglish
A small square of unglazed white porcelain (the rough back of a bathroom tile works too) used for streak tests. It is about 6½ to 7 on the Mohs scale.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.2 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.2 (grade 3)
A small square of unglazed white porcelain (the rough back of a bathroom tile works too) used for streak tests. It is about 6½ to 7 on the Mohs scale.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 1.2 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 9.2 (grade 3)
streamEnglish
A small river of moving water. People also call it a creek or a brook.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.1 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 9.2 (grade 2) · Kindergarten Geography: God Made the Earth: My First Maps, Lesson 4.1 (grade K)
A small river of moving water. People also call it a creek or a brook.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.1 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 9.2 (grade 2) · Kindergarten Geography: God Made the Earth: My First Maps, Lesson 4.1 (grade K)
stream powerEnglish
The rate at which a stream can do work on its bed. It rises steeply with discharge and slope, so a flood many times larger than normal has far more than many times the power.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.4 (grade 6)
The rate at which a stream can do work on its bed. It rises steeply with discharge and slope, so a flood many times larger than normal has far more than many times the power.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.4 (grade 6)
streamgageEnglish
A station beside a creek or river that measures the water level and flow, often sending the numbers online every few minutes.
Grade 4 Earth Science: Weather and Water, Lesson 9.4 (grade 4)
A station beside a creek or river that measures the water level and flow, often sending the numbers online every few minutes.
Grade 4 Earth Science: Weather and Water, Lesson 9.4 (grade 4)
streamlinedEnglish
Shaped to let water or air flow smoothly around it, like a torpedo or a shark, so that there is less drag.
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.2 (grade 6)
Shaped to let water or air flow smoothly around it, like a torpedo or a shark, so that there is less drag.
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.2 (grade 6)
stressEnglish
A force pushing, pulling or shearing rock. Compression squeezes, tension pulls apart, and shear slides one part past another.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.1 (grade 6) · Engineering Design, Robotics & Drones, Lesson 3.1 (grade 9–12) · Grade 7 Engineering & Physics, Lesson 3.1 (grade 7) · +3 more
A force pushing, pulling or shearing rock. Compression squeezes, tension pulls apart, and shear slides one part past another.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.1 (grade 6) · Engineering Design, Robotics & Drones, Lesson 3.1 (grade 9–12) · Grade 7 Engineering & Physics, Lesson 3.1 (grade 7) · +3 more
striationsEnglish
Long, parallel scratches cut into bedrock by stones frozen into the bottom of a moving glacier.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.1 (grade 7) · High School Geology, Lesson 3.3 (grade 9–12)
Long, parallel scratches cut into bedrock by stones frozen into the bottom of a moving glacier.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.1 (grade 7) · High School Geology, Lesson 3.3 (grade 9–12)
strikeEnglish
The compass direction of a horizontal line drawn on a tilted rock layer.
High School Geology, Lesson 8.2 (grade 9–12)
The compass direction of a horizontal line drawn on a tilted rock layer.
High School Geology, Lesson 8.2 (grade 9–12)
strike and dipEnglish
The orientation of a tilted layer: strike is the compass direction of a horizontal line on the layer, and dip is the angle and direction it slopes down; shown by a T-shaped symbol with the dip angle beside it.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.4 (grade 8) · High School Geology, Lesson 9.2 (grade 9–12)
The orientation of a tilted layer: strike is the compass direction of a horizontal line on the layer, and dip is the angle and direction it slopes down; shown by a T-shaped symbol with the dip angle beside it.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.4 (grade 8) · High School Geology, Lesson 9.2 (grade 9–12)
strip croppingEnglish
Planting alternating bands of row crops and close-growing crops such as grass, clover or alfalfa along the contour, so each grass strip catches soil washing off the strip above.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.3 (grade 8)
Planting alternating bands of row crops and close-growing crops such as grass, clover or alfalfa along the contour, so each grass strip catches soil washing off the strip above.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.3 (grade 8)
strip ratioEnglish
The tonnes of waste rock that must be removed for every tonne of ore mined in a surface mine, such as 3:1.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.2 (grade 8)
The tonnes of waste rock that must be removed for every tonne of ore mined in a surface mine, such as 3:1.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.2 (grade 8)
strongholdEnglish
A hard-to-reach place that is easy to keep safe, like a cave in a hill. The Bible calls it a “hold.”
Grade 2 Earth Science: The Earth's Surface, Lesson 4.4 (grade 2)
A hard-to-reach place that is easy to keep safe, like a cave in a hill. The Bible calls it a “hold.”
Grade 2 Earth Science: The Earth's Surface, Lesson 4.4 (grade 2)
subductionEnglish
The sinking of one plate beneath another at a convergent boundary. The sinking plate bends down into the mantle, forming a deep ocean trench.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.3 (grade 6) · High School Geology, Lesson 2.1 (grade 9–12)
The sinking of one plate beneath another at a convergent boundary. The sinking plate bends down into the mantle, forming a deep ocean trench.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.3 (grade 6) · High School Geology, Lesson 2.1 (grade 9–12)
subsoil (B horizon)English
The layer below the topsoil, usually lighter or redder, where clay and minerals washed down from above collect.
Grade 6 Earth Science: The Dynamic Earth, Lesson 9.2 (grade 6)
The layer below the topsoil, usually lighter or redder, where clay and minerals washed down from above collect.
Grade 6 Earth Science: The Dynamic Earth, Lesson 9.2 (grade 6)
sulfurEnglish
A natural yellow element. Chemicals with sulfur in them cause strong smells, like rotten eggs, onions and skunk spray.
Grade 3 Life Science: Plants and Animals Together, Lesson 6.2 (grade 3)
A natural yellow element. Chemicals with sulfur in them cause strong smells, like rotten eggs, onions and skunk spray.
Grade 3 Life Science: Plants and Animals Together, Lesson 6.2 (grade 3)
sulfur dioxideEnglish
A sharp-smelling gas (SO₂) that escapes from magma as it rises; scientists measure how many tons per day a volcano releases.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.2 (grade 6)
A sharp-smelling gas (SO₂) that escapes from magma as it rises; scientists measure how many tons per day a volcano releases.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.2 (grade 6)
summerEnglish
The warmest season of the year, with the longest days.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.2 (grade K)
The warmest season of the year, with the longest days.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.2 (grade K)
summitEnglish
The very top of a mountain.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.1 (grade 2) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 4.1 (grade 3) · Grade 5 Geography: Explorers, Navigators and Missionaries, Lesson 7.4 (grade 5) · +1 more
The very top of a mountain.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.1 (grade 2) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 4.1 (grade 3) · Grade 5 Geography: Explorers, Navigators and Missionaries, Lesson 7.4 (grade 5) · +1 more
sun angleEnglish
How high the sun stands above the horizon. A high sun angle means the rays strike the ground nearly straight on; a low sun angle means they strike at a slant.
Grade 4 Earth Science: Weather and Water, Lesson 8.1 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 5.2 (grade 6)
How high the sun stands above the horizon. A high sun angle means the rays strike the ground nearly straight on; a low sun angle means they strike at a slant.
Grade 4 Earth Science: Weather and Water, Lesson 8.1 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 5.2 (grade 6)
sun timeEnglish
Time told by the sun’s real place in the sky, as a sundial shows it. Also called apparent solar time.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.2 (grade 5)
Time told by the sun’s real place in the sky, as a sundial shows it. Also called apparent solar time.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.2 (grade 5)
sundialEnglish
A device that tells time by the position of a shadow cast by the sun.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.2 (grade 5) · Grade 6 Latin, Lesson 3.2 (grade 6)
A device that tells time by the position of a shadow cast by the sun.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.2 (grade 5) · Grade 6 Latin, Lesson 3.2 (grade 6)
sunlightEnglish
The light from the sun. It looks white, but it has all the colors of the rainbow mixed inside it.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.3 (grade K) · Kindergarten Gardening & Animals, Lesson 5.3 (grade K) · Kindergarten Life Science: God Made the Animals, Lesson 5.3 (grade K) · +1 more
The light from the sun. It looks white, but it has all the colors of the rainbow mixed inside it.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.3 (grade K) · Kindergarten Gardening & Animals, Lesson 5.3 (grade K) · Kindergarten Life Science: God Made the Animals, Lesson 5.3 (grade K) · +1 more
sunsetEnglish
The time in the evening when the sun goes down below the edge of the land and night is coming.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 5.1 (grade K) · Grade 1 Geography: Maps and Journeys, Lesson 2.2 (grade 1)
The time in the evening when the sun goes down below the edge of the land and night is coming.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 5.1 (grade K) · Grade 1 Geography: Maps and Journeys, Lesson 2.2 (grade 1)
supercellEnglish
A large, long-lasting thunderstorm with a rotating updraft. Most strong tornadoes come from supercells.
Grade 4 Earth Science: Weather and Water, Lesson 4.2 (grade 4) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.2 (grade 8) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 8.4 (grade 6)
A large, long-lasting thunderstorm with a rotating updraft. Most strong tornadoes come from supercells.
Grade 4 Earth Science: Weather and Water, Lesson 4.2 (grade 4) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.2 (grade 8) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 8.4 (grade 6)
supercontinentEnglish
A single huge landmass made of most or all of the earth’s continents pressed together.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.1 (grade 6)
A single huge landmass made of most or all of the earth’s continents pressed together.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.1 (grade 6)
superpositionEnglish
Steno’s rule: in a stack of layers that has not been turned over, the bottom layer was laid down first and the top layer last.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.1 (grade 3) · Grade 6 Earth Science: The Dynamic Earth, Lesson 9.4 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 1.2 (grade 7) · +1 more
Steno’s rule: in a stack of layers that has not been turned over, the bottom layer was laid down first and the top layer last.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 3.1 (grade 3) · Grade 6 Earth Science: The Dynamic Earth, Lesson 9.4 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 1.2 (grade 7) · +1 more
surface areaEnglish
How much of something is on the outside, touching the air. A flat, spread-out puddle has more surface area than the same water in a tall glass.
Grade 4 Earth Science: Weather and Water, Lesson 1.2 (grade 4) · Geometry, Lesson 12.2 (grade 9–10) · Grade 5 Life Science: The Human Body, Lesson 1.4 (grade 5) · +2 more
How much of something is on the outside, touching the air. A flat, spread-out puddle has more surface area than the same water in a tall glass.
Grade 4 Earth Science: Weather and Water, Lesson 1.2 (grade 4) · Geometry, Lesson 12.2 (grade 9–10) · Grade 5 Life Science: The Human Body, Lesson 1.4 (grade 5) · +2 more
surface currentEnglish
A current in the top part of the ocean, pushed along mostly by steady winds.
Grade 4 Earth Science: Weather and Water, Lesson 7.2 (grade 4)
A current in the top part of the ocean, pushed along mostly by steady winds.
Grade 4 Earth Science: Weather and Water, Lesson 7.2 (grade 4)
Surtseyan eruptionEnglish
An eruption in shallow water where seawater meets magma and flashes to steam, blasting out jets of wet ash. Named after Surtsey.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.4 (grade 6)
An eruption in shallow water where seawater meets magma and flashes to steam, blasting out jets of wet ash. Named after Surtsey.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.4 (grade 6)
survival rateEnglish
The percent of a group that is still alive after a set time: survivors ÷ starting number × 100.
Grade 6 Life Science: Animal Design and Behavior, Lesson 4.4 (grade 6)
The percent of a group that is still alive after a set time: survivors ÷ starting number × 100.
Grade 6 Life Science: Animal Design and Behavior, Lesson 4.4 (grade 6)
suspensionEnglish
Fine silt and clay carried high in the air by the wind for long distances, as in a dust storm.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.3 (grade 6) · Shop & Trades, Lesson 10.1 (grade 9–12) · Explore Horses and Ponies · Expert, Stop 2.6 (Ages 14+) · +1 more
Fine silt and clay carried high in the air by the wind for long distances, as in a dust storm.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.3 (grade 6) · Shop & Trades, Lesson 10.1 (grade 9–12) · Explore Horses and Ponies · Expert, Stop 2.6 (Ages 14+) · +1 more
sustained yieldEnglish
A harvest that removes only the yearly surplus of a population, so the population can provide the same harvest again year after year.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 7.4 (grade 8)
A harvest that removes only the yearly surplus of a population, so the population can provide the same harvest again year after year.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 7.4 (grade 8)
synoptic observationEnglish
A weather reading taken at the same moment at many stations so that a map of the whole region can be drawn. The first American synoptic observations were telegraphed on November 1, 1870.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.1 (grade 8)
A weather reading taken at the same moment at many stations so that a map of the whole region can be drawn. The first American synoptic observations were telegraphed on November 1, 1870.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.1 (grade 8)
T
tag and recaptureEnglish
A method of marking animals, releasing them and later finding some of them again to learn where they went or how many there are.
Grade 6 Life Science: Animal Design and Behavior, Lesson 2.2 (grade 6)
A method of marking animals, releasing them and later finding some of them again to learn where they went or how many there are.
Grade 6 Life Science: Animal Design and Behavior, Lesson 2.2 (grade 6)
tail flukeEnglish
A flat fin at the end of a tail that pushes against the water, like the tail fin of a shark.
Grade 3 Life Science: Plants and Animals Together, Lesson 7.2 (grade 3)
A flat fin at the end of a tail that pushes against the water, like the tail fin of a shark.
Grade 3 Life Science: Plants and Animals Together, Lesson 7.2 (grade 3)
tail spikeEnglish
A long, sharp, pointed bone at the end of a tail. Stegosaurus had four of them.
Grade 1 Life Science: Animal Homes and Habits, Lesson 7.1 (grade 1)
A long, sharp, pointed bone at the end of a tail. Stegosaurus had four of them.
Grade 1 Life Science: Animal Homes and Habits, Lesson 7.1 (grade 1)
tallyEnglish
A quick count made with marks, usually grouped in fives.
Grade 4 Earth Science: Weather and Water, Lesson 3.4 (grade 4) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.4 (grade 8) · Explore Animals · Ranger, Stop 2.10 (Ages 10–13) · +3 more
A quick count made with marks, usually grouped in fives.
Grade 4 Earth Science: Weather and Water, Lesson 3.4 (grade 4) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.4 (grade 8) · Explore Animals · Ranger, Stop 2.10 (Ages 10–13) · +3 more
tally marksEnglish
Quick counting marks in groups of five: four straight lines with a fifth line across them.
Grade 3 Life Science: Plants and Animals Together, Lesson 5.4 (grade 3)
Quick counting marks in groups of five: four straight lines with a fifth line across them.
Grade 3 Life Science: Plants and Animals Together, Lesson 5.4 (grade 3)
tarEnglish
A sticky brown substance in tobacco smoke that coats the airways and lungs. It contains chemicals that can cause cancer.
Grade 5 Life Science: The Human Body, Lesson 4.4 (grade 5)
A sticky brown substance in tobacco smoke that coats the airways and lungs. It contains chemicals that can cause cancer.
Grade 5 Life Science: The Human Body, Lesson 4.4 (grade 5)
telemetryEnglish
Tracking an animal from a distance with a radio or GPS collar or tag that sends signals about its location.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.2 (grade 8)
Tracking an animal from a distance with a radio or GPS collar or tag that sends signals about its location.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.2 (grade 8)
telescopeEnglish
An instrument with lenses or mirrors that gathers light and makes faraway things look larger and brighter.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.1 (grade 5)
An instrument with lenses or mirrors that gathers light and makes faraway things look larger and brighter.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.1 (grade 5)
temperate zoneEnglish
The zone between the tropics and the polar circles, with warm summers, cold winters and four seasons. Most of the United States is in the northern temperate zone.
Grade 4 Earth Science: Weather and Water, Lesson 8.1 (grade 4)
The zone between the tropics and the polar circles, with warm summers, cold winters and four seasons. Most of the United States is in the northern temperate zone.
Grade 4 Earth Science: Weather and Water, Lesson 8.1 (grade 4)
temperature rangeEnglish
The difference between the highest and lowest temperatures, such as the warmest month minus the coldest month.
Grade 4 Earth Science: Weather and Water, Lesson 8.4 (grade 4)
The difference between the highest and lowest temperatures, such as the warmest month minus the coldest month.
Grade 4 Earth Science: Weather and Water, Lesson 8.4 (grade 4)
tendEnglish
To take care of something so it stays healthy and good, like watering a plant every day.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 8.1 (grade K)
To take care of something so it stays healthy and good, like watering a plant every day.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 8.1 (grade K)
tephraEnglish
All the solid material a volcano throws into the air, from fine ash to pumice to large blocks.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.1 (grade 6)
All the solid material a volcano throws into the air, from fine ash to pumice to large blocks.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.1 (grade 6)
tephra coneEnglish
A hill of loose ash and cinders piled around a vent, easily washed away by waves until something hardens or covers it.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.4 (grade 6)
A hill of loose ash and cinders piled around a vent, easily washed away by waves until something hardens or covers it.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.4 (grade 6)
terraceEnglish
A broad step or ridge built across a slope to shorten the distance water can run and to hold it where it falls.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.3 (grade 8) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 2.3 (grade 3) · Grade 7 Geography: Regions of the World, Lesson 1.2 (grade 7)
A broad step or ridge built across a slope to shorten the distance water can run and to hold it where it falls.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.3 (grade 8) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 2.3 (grade 3) · Grade 7 Geography: Regions of the World, Lesson 1.2 (grade 7)
tetrapodEnglish
An animal with a backbone and four limbs (or descended from such animals), including amphibians, reptiles, birds and mammals.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.3 (grade 8)
An animal with a backbone and four limbs (or descended from such animals), including amphibians, reptiles, birds and mammals.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.3 (grade 8)
the PointersEnglish
Alpha Centauri and Beta Centauri, two bright stars beside the Southern Cross that help locate the south celestial pole.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.3 (grade 5)
Alpha Centauri and Beta Centauri, two bright stars beside the Southern Cross that help locate the south celestial pole.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.3 (grade 5)
theropodEnglish
The group of two-legged, mostly meat-eating dinosaurs such as Tyrannosaurus and Velociraptor, which museum signs name as the closest relatives of birds.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.4 (grade 7) · Explore Dinosaurs · Expert, Stop 1.1 (Ages 14+) · Explore Dinosaurs · Ranger, Stop 1.1 (Ages 10–13) · +1 more
The group of two-legged, mostly meat-eating dinosaurs such as Tyrannosaurus and Velociraptor, which museum signs name as the closest relatives of birds.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.4 (grade 7) · Explore Dinosaurs · Expert, Stop 1.1 (Ages 14+) · Explore Dinosaurs · Ranger, Stop 1.1 (Ages 10–13) · +1 more
thin sectionEnglish
A slice of rock ground so thin that light shines through it, so its tiny crystals can be studied under a microscope.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.2 (grade 3)
A slice of rock ground so thin that light shines through it, so its tiny crystals can be studied under a microscope.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.2 (grade 3)
thoraxEnglish
The middle part of an insect’s body. All six legs, and the wings if it has them, grow from the thorax.
Grade 2 Life Science: Animal Families, Lesson 6.1 (grade 2) · Grade 6 Life Science: Animal Design and Behavior, Lesson 1.3 (grade 6)
The middle part of an insect’s body. All six legs, and the wings if it has them, grow from the thorax.
Grade 2 Life Science: Animal Families, Lesson 6.1 (grade 2) · Grade 6 Life Science: Animal Design and Behavior, Lesson 1.3 (grade 6)
thrust faultEnglish
A gently sloping reverse fault along which one great slab of rock is pushed up and over another. The Himalaya are built on stacked thrust faults.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.3 (grade 6)
A gently sloping reverse fault along which one great slab of rock is pushed up and over another. The Himalaya are built on stacked thrust faults.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.3 (grade 6)
thunderEnglish
The sound made when lightning heats the air so fast that the air bursts outward.
Grade 4 Earth Science: Weather and Water, Lesson 4.4 (grade 4) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.4 (grade K)
The sound made when lightning heats the air so fast that the air bursts outward.
Grade 4 Earth Science: Weather and Water, Lesson 4.4 (grade 4) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.4 (grade K)
thunderstormEnglish
A storm with thunder and lightning, and often heavy rain and strong wind.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.4 (grade K)
A storm with thunder and lightning, and often heavy rain and strong wind.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 4.4 (grade K)
tidal volumeEnglish
The amount of air moved in or out in one quiet, ordinary breath. For a grown-up it is about half a liter.
Grade 5 Life Science: The Human Body, Lesson 4.2 (grade 5)
The amount of air moved in or out in one quiet, ordinary breath. For a grown-up it is about half a liter.
Grade 5 Life Science: The Human Body, Lesson 4.2 (grade 5)
tideEnglish
The sea coming up the beach and going back down again, twice each day.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 1.1 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 6.1 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.4 (grade 3) · +3 more
The sea coming up the beach and going back down again, twice each day.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 1.1 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 6.1 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.4 (grade 3) · +3 more
tide poolEnglish
A little pool of sea water left among the rocks when the tide goes out. Small sea animals live there.
Grade 2 Earth Science: The Earth's Surface, Lesson 6.1 (grade 2)
A little pool of sea water left among the rocks when the tide goes out. Small sea animals live there.
Grade 2 Earth Science: The Earth's Surface, Lesson 6.1 (grade 2)
tide rangeEnglish
The difference in height between high tide and the low tide that comes next.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.4 (grade 5)
The difference in height between high tide and the low tide that comes next.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.4 (grade 5)
TiktaalikEnglish
A large fossil fish found on Ellesmere Island in the Canadian Arctic in 2004, with gills, scales and fins but also a flat head, a neck and sturdy bones inside its front fins.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.3 (grade 8)
A large fossil fish found on Ellesmere Island in the Canadian Arctic in 2004, with gills, scales and fins but also a flat head, a neck and sturdy bones inside its front fins.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.3 (grade 8)
tilapiaEnglish
A flat, silver-gray fish that lives in the Sea of Galilee. People there call it “St. Peter’s fish.”
Grade 2 Life Science: Animal Families, Lesson 5.4 (grade 2)
A flat, silver-gray fish that lives in the Sea of Galilee. People there call it “St. Peter’s fish.”
Grade 2 Life Science: Animal Families, Lesson 5.4 (grade 2)
tillEnglish
The unsorted mix of clay, sand, pebbles and boulders left behind when glacier ice melts.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.1 (grade 7) · High School Geology, Lesson 3.3 (grade 9–12)
The unsorted mix of clay, sand, pebbles and boulders left behind when glacier ice melts.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.1 (grade 7) · High School Geology, Lesson 3.3 (grade 9–12)
tiltEnglish
The lean of Earth’s axis, about 23.5° from straight up-and-down compared with Earth’s path around the Sun. The axis always points toward the North Star.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.1 (grade 5) · Grade 1 Gardening & Animals, Lesson 1.1 (grade 1) · Grade 2 Gardening & Animals, Lesson 1.1 (grade 2) · +1 more
The lean of Earth’s axis, about 23.5° from straight up-and-down compared with Earth’s path around the Sun. The axis always points toward the North Star.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.1 (grade 5) · Grade 1 Gardening & Animals, Lesson 1.1 (grade 1) · Grade 2 Gardening & Animals, Lesson 1.1 (grade 2) · +1 more
tiltmeterEnglish
An instrument like a very sensitive carpenter’s level that measures tiny changes in the slope of the ground as a volcano swells or shrinks.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.2 (grade 6)
An instrument like a very sensitive carpenter’s level that measures tiny changes in the slope of the ground as a volcano swells or shrinks.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.2 (grade 6)
time dilationEnglish
The measured fact that clocks run at different rates depending on how fast they move and how strong the gravity around them is.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.4 (grade 5)
The measured fact that clocks run at different rates depending on how fast they move and how strong the gravity around them is.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 4.4 (grade 5)
time zoneEnglish
A region that keeps the same standard time. Neighboring zones in the United States usually differ by one hour.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.4 (grade 5) · Explore Travel and Faraway Places · Expert, Stop 1.5 (Ages 14+) · Explore Travel and Faraway Places · Ranger, Stop 1.5 (Ages 10–13) · +3 more
A region that keeps the same standard time. Neighboring zones in the United States usually differ by one hour.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 1.4 (grade 5) · Explore Travel and Faraway Places · Expert, Stop 1.5 (Ages 14+) · Explore Travel and Faraway Places · Ranger, Stop 1.5 (Ages 10–13) · +3 more
tissueEnglish
A group of similar cells working together to do one job, such as muscle tissue that pulls or nervous tissue that carries messages.
Grade 5 Life Science: The Human Body, Lesson 1.3 (grade 5)
A group of similar cells working together to do one job, such as muscle tissue that pulls or nervous tissue that carries messages.
Grade 5 Life Science: The Human Body, Lesson 1.3 (grade 5)
tongue stone (glossopetra)English
The old name for a triangular stone found in rock and once thought to have fallen from the sky. Steno showed tongue stones are fossil shark teeth.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.1 (grade 7)
The old name for a triangular stone found in rock and once thought to have fallen from the sky. Steno showed tongue stones are fossil shark teeth.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.1 (grade 7)
tongue stones (glossopetrae)English
Triangular stones found in the rocks of Malta and Italy that people once thought fell from the sky or grew in the ground. Steno showed they are fossil shark teeth.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.4 (grade 6)
Triangular stones found in the rocks of Malta and Italy that people once thought fell from the sky or grew in the ground. Steno showed they are fossil shark teeth.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.4 (grade 6)
tooth shapeEnglish
Whether a tooth is flat, peg-like, leaf-shaped or sharp and curved. The shape gives a clue to what an animal ate.
Grade 2 Earth Science: The Earth's Surface, Lesson 7.3 (grade 2)
Whether a tooth is flat, peg-like, leaf-shaped or sharp and curved. The shape gives a clue to what an animal ate.
Grade 2 Earth Science: The Earth's Surface, Lesson 7.3 (grade 2)
toothed whaleEnglish
A whale with teeth instead of baleen plates. Dolphins, porpoises, orcas and sperm whales are toothed whales, and they echolocate.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.2 (grade 6)
A whale with teeth instead of baleen plates. Dolphins, porpoises, orcas and sperm whales are toothed whales, and they echolocate.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.2 (grade 6)
topographic mapEnglish
A map that shows the shape and elevation of the land using contour lines, along with streams, roads, buildings and place names.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.2 (grade 8) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 1.2 (grade 6)
A map that shows the shape and elevation of the land using contour lines, along with streams, roads, buildings and place names.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.2 (grade 8) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 1.2 (grade 6)
topset, foreset and bottomset bedsEnglish
The three layers of a delta: flat coarse beds on top, sloping sandy beds in front, and thin flat beds of silt and clay spread out on the sea or lake floor.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.2 (grade 6)
The three layers of a delta: flat coarse beds on top, sloping sandy beds in front, and thin flat beds of silt and clay spread out on the sea or lake floor.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.2 (grade 6)
topsoilEnglish
The dark upper layer of soil, rich in humus and roots, where most plant food is held. It is the layer a farm cannot afford to lose.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.1 (grade 8) · Grade 4 Gardening & Animals, Lesson 3.1 (grade 4) · Grade 5 Gardening & Animals, Lesson 3.4 (grade 5) · +2 more
The dark upper layer of soil, rich in humus and roots, where most plant food is held. It is the layer a farm cannot afford to lose.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 1.1 (grade 8) · Grade 4 Gardening & Animals, Lesson 3.1 (grade 4) · Grade 5 Gardening & Animals, Lesson 3.4 (grade 5) · +2 more
topsoil (A horizon)English
The dark upper layer rich in humus, roots and living things, where most plants feed.
Grade 6 Earth Science: The Dynamic Earth, Lesson 9.2 (grade 6)
The dark upper layer rich in humus, roots and living things, where most plants feed.
Grade 6 Earth Science: The Dynamic Earth, Lesson 9.2 (grade 6)
topsoil stockpileEnglish
The A horizon stripped from the mine site before digging and stored in a separate seeded pile so it can be spread back on top at the end. Mixing it with spoil ruins it.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.4 (grade 8)
The A horizon stripped from the mine site before digging and stored in a separate seeded pile so it can be spread back on top at the end. Mixing it with spoil ruins it.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.4 (grade 8)
tornadoEnglish
A violently spinning column of air that reaches from a thunderstorm cloud down to the ground.
Grade 4 Earth Science: Weather and Water, Lesson 4.2 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 8.4 (grade 6)
A violently spinning column of air that reaches from a thunderstorm cloud down to the ground.
Grade 4 Earth Science: Weather and Water, Lesson 4.2 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 8.4 (grade 6)
tornado warningEnglish
A message that a tornado has been seen or shown on radar. Take shelter now.
Grade 4 Earth Science: Weather and Water, Lesson 4.2 (grade 4)
A message that a tornado has been seen or shown on radar. Take shelter now.
Grade 4 Earth Science: Weather and Water, Lesson 4.2 (grade 4)
tornado watchEnglish
A message that the weather is right for tornadoes to form in an area. Be ready.
Grade 4 Earth Science: Weather and Water, Lesson 4.2 (grade 4)
A message that the weather is right for tornadoes to form in an area. Be ready.
Grade 4 Earth Science: Weather and Water, Lesson 4.2 (grade 4)
total magnificationEnglish
Eyepiece power × objective power. A 10× eyepiece with a 40× objective gives 400×.
Grade 7 Life Science: Cells and Microbes, Lesson 1.2 (grade 7)
Eyepiece power × objective power. A 10× eyepiece with a 40× objective gives 400×.
Grade 7 Life Science: Cells and Microbes, Lesson 1.2 (grade 7)
totalityEnglish
The time during a total eclipse when the Sun (or, in a lunar eclipse, the Moon) is completely covered by the shadow.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.3 (grade 5)
The time during a total eclipse when the Sun (or, in a lunar eclipse, the Moon) is completely covered by the shadow.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.3 (grade 5)
touchEnglish
The sense you use to feel things with your skin.
Grade 1 Life Science: Animal Homes and Habits, Lesson 8.4 (grade 1)
The sense you use to feel things with your skin.
Grade 1 Life Science: Animal Homes and Habits, Lesson 8.4 (grade 1)
touch receptorEnglish
A nerve ending in the skin that senses touch, pressure or vibration and sends a signal to the brain. Other receptors sense heat, cold and pain.
Grade 5 Life Science: The Human Body, Lesson 7.4 (grade 5)
A nerve ending in the skin that senses touch, pressure or vibration and sends a signal to the brain. Other receptors sense heat, cold and pain.
Grade 5 Life Science: The Human Body, Lesson 7.4 (grade 5)
trace fossilEnglish
A fossil of something a living thing did or left behind, such as a footprint, a burrow or a nibble mark.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.2 (grade 3) · Explore Dinosaurs · Ranger, Stop 3.3 (Ages 10–13) · Explore Dinosaurs, Stop 3.3 (Ages 7–9) · +1 more
A fossil of something a living thing did or left behind, such as a footprint, a burrow or a nibble mark.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.2 (grade 3) · Explore Dinosaurs · Ranger, Stop 3.3 (Ages 10–13) · Explore Dinosaurs, Stop 3.3 (Ages 7–9) · +1 more
tracheaEnglish
The windpipe: a tube held open by rings of cartilage that carries air from the throat down toward the lungs.
Grade 5 Life Science: The Human Body, Lesson 4.1 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 7.2 (grade 7)
The windpipe: a tube held open by rings of cartilage that carries air from the throat down toward the lungs.
Grade 5 Life Science: The Human Body, Lesson 4.1 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 7.2 (grade 7)
tracheaeEnglish
A branching system of air-filled tubes that carry oxygen from the spiracles directly to the insect’s cells. The finest branches are called tracheoles.
Grade 7 Life Science: Cells and Microbes, Lesson 7.3 (grade 7)
A branching system of air-filled tubes that carry oxygen from the spiracles directly to the insect’s cells. The finest branches are called tracheoles.
Grade 7 Life Science: Cells and Microbes, Lesson 7.3 (grade 7)
trackEnglish
A footprint left by an animal. A row of tracks is called a trackway.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.2 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 7.2 (grade 2) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 7.3 (grade K) · +3 more
A footprint left by an animal. A row of tracks is called a trackway.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 7.2 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 7.2 (grade 2) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 7.3 (grade K) · +3 more
tracking mountEnglish
The stand that holds a telescope and turns it slowly to follow the stars as the earth spins.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.3 (grade 5)
The stand that holds a telescope and turns it slowly to follow the stars as the earth spins.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.3 (grade 5)
trackwayEnglish
A line of footprints made by one animal as it walked or ran.
Grade 2 Earth Science: The Earth's Surface, Lesson 7.2 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.2 (grade 3) · Explore Dinosaurs · Expert, Stop 3.3 (Ages 14+) · +3 more
A line of footprints made by one animal as it walked or ran.
Grade 2 Earth Science: The Earth's Surface, Lesson 7.2 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 5.2 (grade 3) · Explore Dinosaurs · Expert, Stop 3.3 (Ages 14+) · +3 more
trade windsEnglish
Steady winds near the equator. North of the equator they blow from the northeast; south of the equator they blow from the southeast.
Grade 4 Earth Science: Weather and Water, Lesson 7.1 (grade 4) · Explore Travel and Faraway Places · Expert, Stop 3.4 (Ages 14+) · Explore Travel and Faraway Places · Ranger, Stop 3.4 (Ages 10–13) · +3 more
Steady winds near the equator. North of the equator they blow from the northeast; south of the equator they blow from the southeast.
Grade 4 Earth Science: Weather and Water, Lesson 7.1 (grade 4) · Explore Travel and Faraway Places · Expert, Stop 3.4 (Ages 14+) · Explore Travel and Faraway Places · Ranger, Stop 3.4 (Ages 10–13) · +3 more
transcriptionEnglish
Copying a gene’s DNA into mRNA by base pairing. It happens in the nucleus.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.3 (grade 8)
Copying a gene’s DNA into mRNA by base pairing. It happens in the nucleus.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.3 (grade 8)
transducerEnglish
The part of a sonar that changes electricity into sound to send a ping, and changes the returning echo back into electricity.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.3 (grade 6)
The part of a sonar that changes electricity into sound to send a ping, and changes the returning echo back into electricity.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.3 (grade 6)
transectEnglish
A straight line laid across the ground along which samples are taken at set spacing, so the sampling is fair and repeatable.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.1 (grade 8) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.4 (grade 8) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 9.2 (grade 8)
A straight line laid across the ground along which samples are taken at set spacing, so the sampling is fair and repeatable.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.1 (grade 8) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.4 (grade 8) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 9.2 (grade 8)
transform boundaryEnglish
A boundary where two plates slide past each other sideways along a fault, as at the San Andreas Fault in California.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.3 (grade 6)
A boundary where two plates slide past each other sideways along a fault, as at the San Andreas Fault in California.
Grade 6 Earth Science: The Dynamic Earth, Lesson 2.3 (grade 6)
transfusionEnglish
Giving blood (or part of blood) from one person into the veins of another person who needs it.
Grade 5 Life Science: The Human Body, Lesson 3.4 (grade 5)
Giving blood (or part of blood) from one person into the veins of another person who needs it.
Grade 5 Life Science: The Human Body, Lesson 3.4 (grade 5)
transitional formEnglish
A fossil claimed to stand between two major groups, with some features of each. Whether such fossils are true links or complete creatures of their own kind is the point in dispute.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.4 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.3 (grade 8)
A fossil claimed to stand between two major groups, with some features of each. Whether such fossils are true links or complete creatures of their own kind is the point in dispute.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.4 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 5.3 (grade 8)
transpirationEnglish
Water leaving a plant through tiny openings in its leaves as water vapor.
Grade 4 Earth Science: Weather and Water, Lesson 1.2 (grade 4) · Grade 3 Gardening & Animals, Lesson 5.3 (grade 3) · Grade 5 Gardening & Animals, Lesson 5.2 (grade 5) · +3 more
Water leaving a plant through tiny openings in its leaves as water vapor.
Grade 4 Earth Science: Weather and Water, Lesson 1.2 (grade 4) · Grade 3 Gardening & Animals, Lesson 5.3 (grade 3) · Grade 5 Gardening & Animals, Lesson 5.2 (grade 5) · +3 more
trapEnglish
An arrangement of rock layers, such as an upfold (anticline), a fault, a salt dome or a layer that pinches out, that gathers oil and gas in one place under a seal.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.3 (grade 8) · Shop & Trades, Lesson 4.5 (grade 9–12) · Geography and Commerce: Sea Lanes, Straits and Trade Routes, Lesson 4.4 (grade 9–12) · +1 more
An arrangement of rock layers, such as an upfold (anticline), a fault, a salt dome or a layer that pinches out, that gathers oil and gas in one place under a seal.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 4.3 (grade 8) · Shop & Trades, Lesson 4.5 (grade 9–12) · Geography and Commerce: Sea Lanes, Straits and Trade Routes, Lesson 4.4 (grade 9–12) · +1 more
tree cookieEnglish
A thin, round slice cut straight across a log or branch, so you can see its rings.
Grade 1 Life Science: Animal Homes and Habits, Lesson 6.3 (grade 1)
A thin, round slice cut straight across a log or branch, so you can see its rings.
Grade 1 Life Science: Animal Homes and Habits, Lesson 6.3 (grade 1)
tree lineEnglish
The height on a mountain above which trees cannot grow, because it is too cold and windy.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.4 (grade 2) · Grade 2 Geography: Our Country, Coast to Coast, Lesson 4.3 (grade 2) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 6.3 (grade 6)
The height on a mountain above which trees cannot grow, because it is too cold and windy.
Grade 2 Earth Science: The Earth's Surface, Lesson 1.4 (grade 2) · Grade 2 Geography: Our Country, Coast to Coast, Lesson 4.3 (grade 2) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 6.3 (grade 6)
tree ringEnglish
The circle of wood a tree grows in one year. It looks like a light band with a dark line at its outside edge.
Grade 1 Life Science: Animal Homes and Habits, Lesson 6.3 (grade 1)
The circle of wood a tree grows in one year. It looks like a light band with a dark line at its outside edge.
Grade 1 Life Science: Animal Homes and Habits, Lesson 6.3 (grade 1)
trialEnglish
One run of a test. Scientists repeat trials and average them because single measurements always vary a little.
Grade 6 Life Science: Animal Design and Behavior, Lesson 1.4 (grade 6) · Statistics, Lesson 6.1 (grade 11–12) · Statistics, Lesson 8.1 (grade 11–12)
One run of a test. Scientists repeat trials and average them because single measurements always vary a little.
Grade 6 Life Science: Animal Design and Behavior, Lesson 1.4 (grade 6) · Statistics, Lesson 6.1 (grade 11–12) · Statistics, Lesson 8.1 (grade 11–12)
triangulationEnglish
Finding the epicenter by drawing a circle around each of three stations with radius equal to its distance from the earthquake; the circles cross at the epicenter.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.3 (grade 6) · Explore Travel and Faraway Places · Expert, Stop 1.8 (Ages 14+) · Grade 5 Geography: Explorers, Navigators and Missionaries, Lesson 5.2 (grade 5) · +3 more
Finding the epicenter by drawing a circle around each of three stations with radius equal to its distance from the earthquake; the circles cross at the epicenter.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.3 (grade 6) · Explore Travel and Faraway Places · Expert, Stop 1.8 (Ages 14+) · Grade 5 Geography: Explorers, Navigators and Missionaries, Lesson 5.2 (grade 5) · +3 more
tributaryEnglish
A smaller stream or river that flows into a larger one.
Grade 4 Earth Science: Weather and Water, Lesson 6.3 (grade 4) · Grade 2 Geography: Our Country, Coast to Coast, Lesson 3.2 (grade 2) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 2.2 (grade 3) · +3 more
A smaller stream or river that flows into a larger one.
Grade 4 Earth Science: Weather and Water, Lesson 6.3 (grade 4) · Grade 2 Geography: Our Country, Coast to Coast, Lesson 3.2 (grade 2) · Grade 3 Geography: Around the World: Continents and Oceans, Lesson 2.2 (grade 3) · +3 more
TriceratopsEnglish
A dinosaur with three horns on its face. Its name means three-horned face.
Kindergarten Life Science: God Made the Animals, Lesson 7.1 (grade K)
A dinosaur with three horns on its face. Its name means three-horned face.
Kindergarten Life Science: God Made the Animals, Lesson 7.1 (grade K)
trilobiteEnglish
A three-lobed sea animal with a hard shell and jointed legs, common in the lowest fossil-bearing layers and found nowhere alive today.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.2 (grade 7)
A three-lobed sea animal with a hard shell and jointed legs, common in the lowest fossil-bearing layers and found nowhere alive today.
Grade 7 Earth Science: Earth History and the Flood, Lesson 3.2 (grade 7)
Tropic of CancerEnglish
The line of latitude 23.5° north of the equator, where the noon Sun is straight overhead on the June solstice.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.2 (grade 5)
The line of latitude 23.5° north of the equator, where the noon Sun is straight overhead on the June solstice.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.2 (grade 5)
Tropic of CapricornEnglish
The line of latitude 23.5° south of the equator, where the noon Sun is straight overhead on the December solstice.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.2 (grade 5)
The line of latitude 23.5° south of the equator, where the noon Sun is straight overhead on the December solstice.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 7.2 (grade 5)
tropical rainforestEnglish
A thick forest near the equator that is warm all year and gets a great deal of rain, usually more than about 2,000 millimeters (80 inches) a year.
Grade 4 Earth Science: Weather and Water, Lesson 8.3 (grade 4) · Grade 3 Life Science: Plants and Animals Together, Lesson 5.2 (grade 3)
A thick forest near the equator that is warm all year and gets a great deal of rain, usually more than about 2,000 millimeters (80 inches) a year.
Grade 4 Earth Science: Weather and Water, Lesson 8.3 (grade 4) · Grade 3 Life Science: Plants and Animals Together, Lesson 5.2 (grade 3)
tropicsEnglish
The warm zone around the equator, between the Tropic of Cancer (about 23.5° N) and the Tropic of Capricorn (about 23.5° S), where the noon sun can stand straight overhead.
Grade 4 Earth Science: Weather and Water, Lesson 8.1 (grade 4) · Grade 1 Geography: Maps and Journeys, Lesson 5.1 (grade 1) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 4.4 (grade 4)
The warm zone around the equator, between the Tropic of Cancer (about 23.5° N) and the Tropic of Capricorn (about 23.5° S), where the noon sun can stand straight overhead.
Grade 4 Earth Science: Weather and Water, Lesson 8.1 (grade 4) · Grade 1 Geography: Maps and Journeys, Lesson 5.1 (grade 1) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 4.4 (grade 4)
true northEnglish
The direction toward the North Pole along Earth’s surface. A compass points to magnetic north, which in many places is a few degrees away from true north.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.1 (grade 5) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 7.1 (grade 8)
The direction toward the North Pole along Earth’s surface. A compass points to magnetic north, which in many places is a few degrees away from true north.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.1 (grade 5) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 7.1 (grade 8)
true-breedingEnglish
A plant line that always produces offspring with the same form of a trait when it pollinates itself, such as tall plants that give only tall plants.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.1 (grade 8)
A plant line that always produces offspring with the same form of a trait when it pollinates itself, such as tall plants that give only tall plants.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 1.1 (grade 8)
tsunamiEnglish
A series of long sea waves set off when a large amount of water is suddenly pushed, as by a collapsing volcano or an undersea earthquake.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.2 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 4.4 (grade 6)
A series of long sea waves set off when a large amount of water is suddenly pushed, as by a collapsing volcano or an undersea earthquake.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.2 (grade 6) · Grade 6 Earth Science: The Dynamic Earth, Lesson 4.4 (grade 6)
tube feetEnglish
Hundreds of tiny, soft, water-filled tubes under a sea star’s arms that it uses to walk, grip and pull.
Grade 4 Life Science: Classification, Lesson 3.4 (grade 4)
Hundreds of tiny, soft, water-filled tubes under a sea star’s arms that it uses to walk, grip and pull.
Grade 4 Life Science: Classification, Lesson 3.4 (grade 4)
tube-shaped flowerEnglish
A flower whose petals form a long, narrow tube with nectar at the bottom, often visited by hummingbirds and moths with long tongues or beaks.
Grade 3 Life Science: Plants and Animals Together, Lesson 3.3 (grade 3)
A flower whose petals form a long, narrow tube with nectar at the bottom, often visited by hummingbirds and moths with long tongues or beaks.
Grade 3 Life Science: Plants and Animals Together, Lesson 3.3 (grade 3)
tumbleEnglish
To roll and bump over and over.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.3 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.3 (grade K)
To roll and bump over and over.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.3 (grade 1) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 1.3 (grade K)
tuned mass damperEnglish
A very heavy weight hung near the top of a tall building and tuned to swing against the building’s motion, soaking up energy and reducing sway.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.1 (grade 6) · Grade 5 Engineering & Physics, Lesson 3.4 (grade 5) · Grade 7 Engineering & Physics, Lesson 3.4 (grade 7)
A very heavy weight hung near the top of a tall building and tuned to swing against the building’s motion, soaking up energy and reducing sway.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.1 (grade 6) · Grade 5 Engineering & Physics, Lesson 3.4 (grade 5) · Grade 7 Engineering & Physics, Lesson 3.4 (grade 7)
tunnelEnglish
A long hole a worm makes as it pushes and eats its way through the dirt.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.2 (grade K) · Grade 2 Gardening & Animals, Lesson 2.2 (grade 2) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 7.2 (grade 4)
A long hole a worm makes as it pushes and eats its way through the dirt.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 2.2 (grade K) · Grade 2 Gardening & Animals, Lesson 2.2 (grade 2) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 7.2 (grade 4)
turbidity currentEnglish
A fast, dense flow of sediment-laden water down an underwater slope that deposits a graded bed called a turbidite.
High School Geology, Lesson 6.1 (grade 9–12)
A fast, dense flow of sediment-laden water down an underwater slope that deposits a graded bed called a turbidite.
High School Geology, Lesson 6.1 (grade 9–12)
tuskEnglish
A very long upper incisor tooth made of ivory. Mammoth tusks grew all their lives and curve more strongly than elephant tusks.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.2 (grade 7) · Explore Animals · Expert, Stop 1.2 (Ages 14+) · Explore Animals · Ranger, Stop 1.2 (Ages 10–13) · +2 more
A very long upper incisor tooth made of ivory. Mammoth tusks grew all their lives and curve more strongly than elephant tusks.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.2 (grade 7) · Explore Animals · Expert, Stop 1.2 (Ages 14+) · Explore Animals · Ranger, Stop 1.2 (Ages 10–13) · +2 more
twinklingEnglish
The quick shimmering of starlight caused by moving pockets of warmer and cooler air bending the light.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.2 (grade 5)
The quick shimmering of starlight caused by moving pockets of warmer and cooler air bending the light.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 6.2 (grade 5)
two-point thresholdEnglish
The smallest distance between two points touching the skin at which a person can still feel two points instead of one.
Grade 5 Life Science: The Human Body, Lesson 7.4 (grade 5)
The smallest distance between two points touching the skin at which a person can still feel two points instead of one.
Grade 5 Life Science: The Human Body, Lesson 7.4 (grade 5)
tympanumEnglish
The round eardrum on the outside of a frog’s head, just behind each eye.
Grade 7 Life Science: Cells and Microbes, Lesson 8.2 (grade 7)
The round eardrum on the outside of a frog’s head, just behind each eye.
Grade 7 Life Science: Cells and Microbes, Lesson 8.2 (grade 7)
Tyrannosaurus rexEnglish
A huge meat-eating dinosaur that walked on two strong legs and had a giant head, sharp teeth and small arms. Its name means “tyrant lizard king.”
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.2 (grade 3) · Explore Dinosaurs · Expert, Stop 2.7 (Ages 14+) · Explore Dinosaurs · Ranger, Stop 2.7 (Ages 10–13) · +1 more
A huge meat-eating dinosaur that walked on two strong legs and had a giant head, sharp teeth and small arms. Its name means “tyrant lizard king.”
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 6.2 (grade 3) · Explore Dinosaurs · Expert, Stop 2.7 (Ages 14+) · Explore Dinosaurs · Ranger, Stop 2.7 (Ages 10–13) · +1 more
U
ultrasound imagingEnglish
Using very high-pitched sound echoes to make pictures of the inside of the body, such as a baby before birth.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.3 (grade 6)
Using very high-pitched sound echoes to make pictures of the inside of the body, such as a baby before birth.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.3 (grade 6)
umbraEnglish
The dark inner part of a shadow, where the light is blocked completely. Inside the Moon’s umbra you see a total solar eclipse.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.3 (grade 5)
The dark inner part of a shadow, where the light is blocked completely. Inside the Moon’s umbra you see a total solar eclipse.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.3 (grade 5)
unconfined aquiferEnglish
An aquifer open to the surface above, so its top is the water table and it is recharged directly by rain soaking down.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.2 (grade 8)
An aquifer open to the surface above, so its top is the water table and it is recharged directly by rain soaking down.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.2 (grade 8)
unconformityEnglish
A surface in the rock where one set of layers lies on top of another that was tilted or worn away first. Hutton’s unconformity at Siccar Point is the most famous.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.3 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 2.2 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.3 (grade 8) · +2 more
A surface in the rock where one set of layers lies on top of another that was tilted or worn away first. Hutton’s unconformity at Siccar Point is the most famous.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.3 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 2.2 (grade 7) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.3 (grade 8) · +2 more
underclayEnglish
The fine clay layer often found directly beneath a coal seam.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.4 (grade 7)
The fine clay layer often found directly beneath a coal seam.
Grade 7 Earth Science: Earth History and the Flood, Lesson 2.4 (grade 7)
undercuttingEnglish
The eating away of soft rock at the base of a cliff so that the harder rock above is left hanging and eventually breaks off.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.1 (grade 6)
The eating away of soft rock at the base of a cliff so that the harder rock above is left hanging and eventually breaks off.
Grade 6 Earth Science: The Dynamic Earth, Lesson 6.1 (grade 6)
undisturbedEnglish
Layers that have not been folded over, pushed on top of one another by faulting, or had molten rock squeezed between them since they formed.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.2 (grade 7)
Layers that have not been folded over, pushed on top of one another by faulting, or had molten rock squeezed between them since they formed.
Grade 7 Earth Science: Earth History and the Flood, Lesson 1.2 (grade 7)
unicellularEnglish
Made of only one cell, such as a bacterium or an amoeba.
Grade 7 Life Science: Cells and Microbes, Lesson 2.1 (grade 7)
Made of only one cell, such as a bacterium or an amoeba.
Grade 7 Life Science: Cells and Microbes, Lesson 2.1 (grade 7)
unidirectional airflowEnglish
Air moving in only one direction through the lung, instead of in and out the same way.
Grade 7 Life Science: Cells and Microbes, Lesson 7.2 (grade 7)
Air moving in only one direction through the lung, instead of in and out the same way.
Grade 7 Life Science: Cells and Microbes, Lesson 7.2 (grade 7)
uniformitarianismEnglish
The idea, pressed by Hutton and Lyell, that the earth’s past should be explained only by processes seen today, acting at about today’s rates, over immense time.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.3 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 4.4 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 7.2 (grade 7) · +2 more
The idea, pressed by Hutton and Lyell, that the earth’s past should be explained only by processes seen today, acting at about today’s rates, over immense time.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.3 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 4.4 (grade 7) · Grade 7 Earth Science: Earth History and the Flood, Lesson 7.2 (grade 7) · +2 more
uniformity of lawEnglish
The principle that the laws of nature (gravity, chemistry, the behavior of water) were the same in the past as now. Nearly all scientists, including creation geologists, accept this.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.3 (grade 6)
The principle that the laws of nature (gravity, chemistry, the behavior of water) were the same in the past as now. Nearly all scientists, including creation geologists, accept this.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.3 (grade 6)
uniformity of rateEnglish
The further claim that processes ran at about the same speed in the past as they do now. This is the part that catastrophists, old and new, reject.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.3 (grade 6)
The further claim that processes ran at about the same speed in the past as they do now. This is the part that catastrophists, old and new, reject.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.3 (grade 6)
universal gravitationEnglish
Newton’s discovery that the same gravity that pulls an apple to the ground reaches out into space and holds the Moon and the planets in their orbits.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.3 (grade 5)
Newton’s discovery that the same gravity that pulls an apple to the ground reaches out into space and holds the Moon and the planets in their orbits.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 5.3 (grade 5)
upliftEnglish
The raising of rock to a higher elevation. Uplift is measured today in millimeters per year.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.3 (grade 6) · Architecture & Civil Engineering, Lesson 8.5 (grade 9–12)
The raising of rock to a higher elevation. Uplift is measured today in millimeters per year.
Grade 6 Earth Science: The Dynamic Earth, Lesson 5.3 (grade 6) · Architecture & Civil Engineering, Lesson 8.5 (grade 9–12)
upstreamEnglish
The direction the weather is coming from. In the middle latitudes, that is usually the west.
Grade 4 Earth Science: Weather and Water, Lesson 5.4 (grade 4) · Grade 4 Engineering & Physics, Lesson 6.3 (grade 4) · Grade 1 Geography: Maps and Journeys, Lesson 8.3 (grade 1) · +3 more
The direction the weather is coming from. In the middle latitudes, that is usually the west.
Grade 4 Earth Science: Weather and Water, Lesson 5.4 (grade 4) · Grade 4 Engineering & Physics, Lesson 6.3 (grade 4) · Grade 1 Geography: Maps and Journeys, Lesson 8.3 (grade 1) · +3 more
UranusEnglish
The seventh planet from the Sun, a pale blue-green giant tipped over on its side. It was the first planet found with a telescope.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.3 (grade 5)
The seventh planet from the Sun, a pale blue-green giant tipped over on its side. It was the first planet found with a telescope.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 3.3 (grade 5)
U-shaped valleyEnglish
A valley with steep sides and a wide, rounded bottom, carved by a glacier.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.2 (grade 2) · Explore Travel and Faraway Places · Expert, Stop 4.5 (Ages 14+) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 4.4 (grade 6)
A valley with steep sides and a wide, rounded bottom, carved by a glacier.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.2 (grade 2) · Explore Travel and Faraway Places · Expert, Stop 4.5 (Ages 14+) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 4.4 (grade 6)
UtnapishtimEnglish
The flood survivor in the Babylonian Epic of Gilgamesh; the Sumerian version calls him Ziusudra and the Babylonian Atrahasis poem calls him Atrahasis.
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.3 (grade 7)
The flood survivor in the Babylonian Epic of Gilgamesh; the Sumerian version calls him Ziusudra and the Babylonian Atrahasis poem calls him Atrahasis.
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.3 (grade 7)
V
vaccineEnglish
Something given to a person to teach the body to fight a disease before the person ever meets it. The word comes from the Latin vacca, “cow,” because the first one came from cowpox.
Grade 5 Life Science: The Human Body, Lesson 8.1 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 4.4 (grade 7)
Something given to a person to teach the body to fight a disease before the person ever meets it. The word comes from the Latin vacca, “cow,” because the first one came from cowpox.
Grade 5 Life Science: The Human Body, Lesson 8.1 (grade 5) · Grade 7 Life Science: Cells and Microbes, Lesson 4.4 (grade 7)
valleyEnglish
A low place between hills or mountains. Water often runs along the bottom of a valley.
Grade 2 Earth Science: The Earth's Surface, Lesson 9.1 (grade 2) · Kindergarten Geography: God Made the Earth: My First Maps, Lesson 3.2 (grade K)
A low place between hills or mountains. Water often runs along the bottom of a valley.
Grade 2 Earth Science: The Earth's Surface, Lesson 9.1 (grade 2) · Kindergarten Geography: God Made the Earth: My First Maps, Lesson 3.2 (grade K)
van der Waals forceEnglish
A very weak attraction between molecules that are extremely close together, only a few nanometers apart. Millions of them added together let a gecko cling.
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.3 (grade 6)
A very weak attraction between molecules that are extremely close together, only a few nanometers apart. Millions of them added together let a gecko cling.
Grade 6 Life Science: Animal Design and Behavior, Lesson 8.3 (grade 6)
vane asymmetryEnglish
In flight feathers, the vane on the leading edge is narrower than the vane on the trailing edge. Symmetrical vanes mark a feather not used for flight.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.4 (grade 7)
In flight feathers, the vane on the leading edge is narrower than the vane on the trailing edge. Symmetrical vanes mark a feather not used for flight.
Grade 7 Earth Science: Earth History and the Flood, Lesson 6.4 (grade 7)
vascular plantEnglish
A plant with tiny tubes inside its roots, stems and leaves that carry water and food. Ferns, conifers and flowering plants are vascular.
Grade 4 Life Science: Classification, Lesson 6.1 (grade 4)
A plant with tiny tubes inside its roots, stems and leaves that carry water and food. Ferns, conifers and flowering plants are vascular.
Grade 4 Life Science: Classification, Lesson 6.1 (grade 4)
vector dataEnglish
Map features stored as shapes: points (a well), lines (a road or stream) and polygons (a rock unit, a county), each defined by coordinates.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.3 (grade 8) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 7.4 (grade 8)
Map features stored as shapes: points (a well), lines (a road or stream) and polygons (a rock unit, a county), each defined by coordinates.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 5.3 (grade 8) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 7.4 (grade 8)
veinEnglish
A long, thin crack in rock that has been filled with a different rock or mineral.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.1 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.2 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.3 (grade 3) · +3 more
A long, thin crack in rock that has been filled with a different rock or mineral.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.1 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.2 (grade 3) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 7.3 (grade 3) · +3 more
VelociraptorEnglish
A small, quick meat-eating dinosaur about the size of a big dog. Its name means swift thief.
Kindergarten Life Science: God Made the Animals, Lesson 7.3 (grade K)
A small, quick meat-eating dinosaur about the size of a big dog. Its name means swift thief.
Kindergarten Life Science: God Made the Animals, Lesson 7.3 (grade K)
velocityEnglish
How fast the water moves, measured in meters per second (or feet per second).
Grade 4 Earth Science: Weather and Water, Lesson 9.4 (grade 4) · Grade 6 Engineering & Physics, Lesson 1.1 (grade 6) · Grade 8 Engineering & Physics, Lesson 1.1 (grade 8)
How fast the water moves, measured in meters per second (or feet per second).
Grade 4 Earth Science: Weather and Water, Lesson 9.4 (grade 4) · Grade 6 Engineering & Physics, Lesson 1.1 (grade 6) · Grade 8 Engineering & Physics, Lesson 1.1 (grade 8)
ventilationEnglish
Moving fresh air through a mine with large fans so that methane is diluted below 1 percent and oxygen stays high. Airflow equals air speed times the cross-section area of the tunnel.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.3 (grade 8)
Moving fresh air through a mine with large fans so that methane is diluted below 1 percent and oxygen stays high. Airflow equals air speed times the cross-section area of the tunnel.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 3.3 (grade 8)
vertebrateEnglish
An animal with a backbone made of small bones called vertebrae. Fish, amphibians, reptiles, birds and mammals are vertebrates.
Grade 4 Life Science: Classification, Lesson 2.1 (grade 4) · Grade 5 Life Science: The Human Body, Lesson 9.3 (grade 5)
An animal with a backbone made of small bones called vertebrae. Fish, amphibians, reptiles, birds and mammals are vertebrates.
Grade 4 Life Science: Classification, Lesson 2.1 (grade 4) · Grade 5 Life Science: The Human Body, Lesson 9.3 (grade 5)
vesicleEnglish
A small hole in lava rock left by a gas bubble that was trapped as the lava hardened.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.3 (grade 3)
A small hole in lava rock left by a gas bubble that was trapped as the lava hardened.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.3 (grade 3)
veterinarian (vet)English
A doctor for animals.
Kindergarten Life Science: God Made the Animals, Lesson 2.4 (grade K)
A doctor for animals.
Kindergarten Life Science: God Made the Animals, Lesson 2.4 (grade K)
vibrationEnglish
A quick back-and-forth movement. Every sound starts as a vibration that pushes on the air.
Grade 5 Life Science: The Human Body, Lesson 7.2 (grade 5)
A quick back-and-forth movement. Every sound starts as a vibration that pushes on the air.
Grade 5 Life Science: The Human Body, Lesson 7.2 (grade 5)
villiEnglish
Millions of tiny, finger-like bumps lining the small intestine that give it a huge surface for taking in food.
Grade 5 Life Science: The Human Body, Lesson 5.3 (grade 5)
Millions of tiny, finger-like bumps lining the small intestine that give it a huge surface for taking in food.
Grade 5 Life Science: The Human Body, Lesson 5.3 (grade 5)
visibilityEnglish
How far you can see clearly through the air.
Grade 4 Earth Science: Weather and Water, Lesson 4.3 (grade 4)
How far you can see clearly through the air.
Grade 4 Earth Science: Weather and Water, Lesson 4.3 (grade 4)
visual aidEnglish
A map, graph, table or object a speaker shows so the audience can see the evidence while hearing the claim.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.4 (grade 8)
A map, graph, table or object a speaker shows so the audience can see the evidence while hearing the claim.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.4 (grade 8)
vital capacityEnglish
The most air a person can breathe out after taking the deepest breath possible.
Grade 5 Life Science: The Human Body, Lesson 4.2 (grade 5)
The most air a person can breathe out after taking the deepest breath possible.
Grade 5 Life Science: The Human Body, Lesson 4.2 (grade 5)
volcanic aerosolsEnglish
Tiny ash and sulfur droplets thrown high into the atmosphere by eruptions; they reflect sunlight and cool the ground below.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.3 (grade 7)
Tiny ash and sulfur droplets thrown high into the atmosphere by eruptions; they reflect sunlight and cool the ground below.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.3 (grade 7)
volcanic ashEnglish
Tiny bits of volcanic rock and glass, smaller than 2 mm, blown out of a volcano. It is hard and gritty, not soft like fireplace ash.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.1 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 3.1 (grade 6)
Tiny bits of volcanic rock and glass, smaller than 2 mm, blown out of a volcano. It is hard and gritty, not soft like fireplace ash.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.1 (grade 6) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 3.1 (grade 6)
Volcanic Explosivity Index (VEI)English
A scale from 0 to 8 that ranks eruptions by how much tephra they throw out; each step up means about ten times more material.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.2 (grade 6)
A scale from 0 to 8 that ranks eruptions by how much tephra they throw out; each step up means about ten times more material.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.2 (grade 6)
volcanic glassEnglish
Glass made by a volcano, not by people. Obsidian is volcanic glass.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.3 (grade 2)
Glass made by a volcano, not by people. Obsidian is volcanic glass.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.3 (grade 2)
volcanoEnglish
An opening in the ground where hot melted rock, ash and gas come out. The mountain around the opening is called a volcano too.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.1 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.1 (grade 3) · Explore Travel and Faraway Places, Stop 4.7 (Ages 7–9) · +3 more
An opening in the ground where hot melted rock, ash and gas come out. The mountain around the opening is called a volcano too.
Grade 2 Earth Science: The Earth's Surface, Lesson 2.1 (grade 2) · Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 2.1 (grade 3) · Explore Travel and Faraway Places, Stop 4.7 (Ages 7–9) · +3 more
volcano observatoryEnglish
A station where scientists watch a volcano day and night with instruments; the United States Geological Survey runs five, in Alaska, the Cascades, California, Hawaii and Yellowstone.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.2 (grade 6)
A station where scientists watch a volcano day and night with instruments; the United States Geological Survey runs five, in Alaska, the Cascades, California, Hawaii and Yellowstone.
Grade 6 Earth Science: The Dynamic Earth, Lesson 8.2 (grade 6)
volvaEnglish
A cup or sac around the base of the stalk of an Amanita, left from the “egg” the young mushroom grew in. It is often buried in soil or leaves.
Grade 7 Life Science: Cells and Microbes, Lesson 6.4 (grade 7)
A cup or sac around the base of the stalk of an Amanita, left from the “egg” the young mushroom grew in. It is often buried in soil or leaves.
Grade 7 Life Science: Cells and Microbes, Lesson 6.4 (grade 7)
voucher specimenEnglish
A specimen kept as proof of what was found in a study, so that others can check the identification later.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 9.4 (grade 8)
A specimen kept as proof of what was found in a study, so that others can check the identification later.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 9.4 (grade 8)
W
waningEnglish
Shrinking. A waning moon shows a little less light each night.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.2 (grade 1) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.2 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.3 (grade 5)
Shrinking. A waning moon shows a little less light each night.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.2 (grade 1) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.2 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.3 (grade 5)
warm currentEnglish
A current that carries warm water from near the equator toward the poles.
Grade 4 Earth Science: Weather and Water, Lesson 7.2 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 7.2 (grade 6)
A current that carries warm water from near the equator toward the poles.
Grade 4 Earth Science: Weather and Water, Lesson 7.2 (grade 4) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 7.2 (grade 6)
warm frontEnglish
A front where warm air slides up and over cooler air. Map symbol: a red line with half circles.
Grade 4 Earth Science: Weather and Water, Lesson 5.3 (grade 4)
A front where warm air slides up and over cooler air. Map symbol: a red line with half circles.
Grade 4 Earth Science: Weather and Water, Lesson 5.3 (grade 4)
warm-blooded (endotherm)English
An animal that makes its own body heat from the food it eats and keeps a steady body temperature. Birds and mammals are warm-blooded.
Grade 4 Life Science: Classification, Lesson 2.3 (grade 4)
An animal that makes its own body heat from the food it eats and keeps a steady body temperature. Birds and mammals are warm-blooded.
Grade 4 Life Science: Classification, Lesson 2.3 (grade 4)
watch and warningEnglish
A watch means conditions are favorable for dangerous weather over a large area in the coming hours; a warning means the danger is happening or about to happen in a specific place, so act now.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.1 (grade 8)
A watch means conditions are favorable for dangerous weather over a large area in the coming hours; a warning means the danger is happening or about to happen in a specific place, so act now.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.1 (grade 8)
water columnEnglish
The height of water standing in the well: total depth minus depth to water.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.2 (grade 8)
The height of water standing in the well: total depth minus depth to water.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.2 (grade 8)
water cycleEnglish
The path water travels over and over: from the sea and land up into the air, back down as rain or snow, and downhill to the sea again.
Grade 4 Earth Science: Weather and Water, Lesson 1.1 (grade 4) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 3.2 (grade K) · Grade 1 Geography: Maps and Journeys, Lesson 4.2 (grade 1)
The path water travels over and over: from the sea and land up into the air, back down as rain or snow, and downhill to the sea again.
Grade 4 Earth Science: Weather and Water, Lesson 1.1 (grade 4) · Kindergarten Earth Science: God Made the Ground and Sky, Lesson 3.2 (grade K) · Grade 1 Geography: Maps and Journeys, Lesson 4.2 (grade 1)
water gapEnglish
A notch where a river cuts straight through a ridge instead of going around it, as at the Delaware Water Gap.
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.4 (grade 7) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 3.4 (grade 8)
A notch where a river cuts straight through a ridge instead of going around it, as at the Delaware Water Gap.
Grade 7 Earth Science: Earth History and the Flood, Lesson 4.4 (grade 7) · Grade 8 Geography: Rivers, Ports and Straits, Lesson 3.4 (grade 8)
water tableEnglish
The top of the underground zone where every space is filled with water.
Grade 4 Earth Science: Weather and Water, Lesson 1.4 (grade 4) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.1 (grade 8) · Grade 7 Geography: Regions of the World, Lesson 3.2 (grade 7) · +1 more
The top of the underground zone where every space is filled with water.
Grade 4 Earth Science: Weather and Water, Lesson 1.4 (grade 4) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.1 (grade 8) · Grade 7 Geography: Regions of the World, Lesson 3.2 (grade 7) · +1 more
water vaporEnglish
Water that has turned into a gas. It is in the air all around us, but we cannot see it.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 4.2 (grade 1) · Grade 4 Earth Science: Weather and Water, Lesson 1.2 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 3.1 (grade 4) · +2 more
Water that has turned into a gas. It is in the air all around us, but we cannot see it.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 4.2 (grade 1) · Grade 4 Earth Science: Weather and Water, Lesson 1.2 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 3.1 (grade 4) · +2 more
water vapor capacityEnglish
The most water vapor air can hold at a given temperature. It roughly doubles for every 10 °C of warming.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.3 (grade 7)
The most water vapor air can hold at a given temperature. It roughly doubles for every 10 °C of warming.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.3 (grade 7)
water vascular systemEnglish
A set of water-filled canals inside an echinoderm that pushes water into the tube feet to move them.
Grade 4 Life Science: Classification, Lesson 3.4 (grade 4)
A set of water-filled canals inside an echinoderm that pushes water into the tube feet to move them.
Grade 4 Life Science: Classification, Lesson 3.4 (grade 4)
waterlineEnglish
The line where the water touches something that is floating.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.3 (grade 2)
The line where the water touches something that is floating.
Grade 2 Earth Science: The Earth's Surface, Lesson 5.3 (grade 2)
waterproofEnglish
Made so that water cannot soak through.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 8.2 (grade 1)
Made so that water cannot soak through.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 8.2 (grade 1)
watershedEnglish
All the land that drains into one river, lake or bay. Rain that falls anywhere in a watershed ends up flowing to the same place. Also called a drainage basin.
Grade 4 Earth Science: Weather and Water, Lesson 6.3 (grade 4) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 4.1 (grade 4) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 5.1 (grade 4) · +1 more
All the land that drains into one river, lake or bay. Rain that falls anywhere in a watershed ends up flowing to the same place. Also called a drainage basin.
Grade 4 Earth Science: Weather and Water, Lesson 6.3 (grade 4) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 4.1 (grade 4) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 5.1 (grade 4) · +1 more
waveEnglish
A hump of water that moves across a lake or the sea. Wind pushing on the water makes waves.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.4 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 6.2 (grade 2) · Grade 4 Earth Science: Weather and Water, Lesson 7.2 (grade 4) · +2 more
A hump of water that moves across a lake or the sea. Wind pushing on the water makes waves.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.4 (grade 1) · Grade 2 Earth Science: The Earth's Surface, Lesson 6.2 (grade 2) · Grade 4 Earth Science: Weather and Water, Lesson 7.2 (grade 4) · +2 more
wave erosionEnglish
The wearing away of a coast by the pounding of waves, which cuts cliffs and rounds stones into boulders and pebbles.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.4 (grade 6)
The wearing away of a coast by the pounding of waves, which cuts cliffs and rounds stones into boulders and pebbles.
Grade 6 Earth Science: The Dynamic Earth, Lesson 3.4 (grade 6)
wave trainEnglish
The series of waves in a tsunami, arriving minutes to an hour apart; the first is often not the largest.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.4 (grade 6)
The series of waves in a tsunami, arriving minutes to an hour apart; the first is often not the largest.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.4 (grade 6)
wavelengthEnglish
The distance from one wave crest to the next; a tsunami’s wavelength in the open ocean can be more than 100 km.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.4 (grade 6) · Grade 6 Engineering & Physics, Lesson 9.3 (grade 6) · Physics, Lesson 9.2 (grade 11–12) · +1 more
The distance from one wave crest to the next; a tsunami’s wavelength in the open ocean can be more than 100 km.
Grade 6 Earth Science: The Dynamic Earth, Lesson 4.4 (grade 6) · Grade 6 Engineering & Physics, Lesson 9.3 (grade 6) · Physics, Lesson 9.2 (grade 11–12) · +1 more
waxingEnglish
Growing. A waxing moon shows a little more light each night.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.2 (grade 1) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.2 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.3 (grade 5)
Growing. A waxing moon shows a little more light each night.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 6.2 (grade 1) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 2.2 (grade 5) · Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 9.3 (grade 5)
wear awayEnglish
To rub off a little bit at a time until a part is gone.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.3 (grade 1)
To rub off a little bit at a time until a part is gone.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 3.3 (grade 1)
weatherEnglish
What the air outside is like right now: hot or cold, wet or dry, still or windy.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 8.2 (grade 1) · Grade 1 Earth Science: Rocks, Water and Weather, Lesson 8.4 (grade 1) · Grade 4 Earth Science: Weather and Water, Lesson 8.4 (grade 4) · +3 more
What the air outside is like right now: hot or cold, wet or dry, still or windy.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 8.2 (grade 1) · Grade 1 Earth Science: Rocks, Water and Weather, Lesson 8.4 (grade 1) · Grade 4 Earth Science: Weather and Water, Lesson 8.4 (grade 4) · +3 more
weather chartEnglish
A calendar or table where we write down the weather each day.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 8.4 (grade 1)
A calendar or table where we write down the weather each day.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 8.4 (grade 1)
weather mapEnglish
A map that shows the weather at many places at the same moment.
Grade 4 Earth Science: Weather and Water, Lesson 5.2 (grade 4)
A map that shows the weather at many places at the same moment.
Grade 4 Earth Science: Weather and Water, Lesson 5.2 (grade 4)
weather sayingEnglish
An old rhyme or rule of thumb about forecasting, such as “red sky at night,” that can be tested with careful records.
Grade 4 Earth Science: Weather and Water, Lesson 9.2 (grade 4)
An old rhyme or rule of thumb about forecasting, such as “red sky at night,” that can be tested with careful records.
Grade 4 Earth Science: Weather and Water, Lesson 9.2 (grade 4)
weather stationEnglish
A place where the weather is measured and recorded, often at the same times every day.
Grade 4 Earth Science: Weather and Water, Lesson 5.2 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 9.1 (grade 4)
A place where the weather is measured and recorded, often at the same times every day.
Grade 4 Earth Science: Weather and Water, Lesson 5.2 (grade 4) · Grade 4 Earth Science: Weather and Water, Lesson 9.1 (grade 4)
weatheringEnglish
The breaking of rock into smaller pieces by water, ice, wind, roots and other forces.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.4 (grade 3) · Grade 1 Gardening & Animals, Lesson 3.4 (grade 1) · Grade 7 Gardening & Animals, Lesson 3.1 (grade 7) · +2 more
The breaking of rock into smaller pieces by water, ice, wind, roots and other forces.
Grade 3 Earth Science: Rocks, Minerals and Fossils, Lesson 4.4 (grade 3) · Grade 1 Gardening & Animals, Lesson 3.4 (grade 1) · Grade 7 Gardening & Animals, Lesson 3.1 (grade 7) · +2 more
webbed feetEnglish
Feet with skin stretched between the toes, like a paddle, for pushing through water.
Grade 1 Life Science: Animal Homes and Habits, Lesson 2.2 (grade 1) · Grade 2 Life Science: Animal Families, Lesson 1.4 (grade 2)
Feet with skin stretched between the toes, like a paddle, for pushing through water.
Grade 1 Life Science: Animal Homes and Habits, Lesson 2.2 (grade 1) · Grade 2 Life Science: Animal Families, Lesson 1.4 (grade 2)
webbed footEnglish
A foot with skin stretched between the toes, which pushes against the water like a paddle.
Grade 4 Life Science: Classification, Lesson 4.2 (grade 4)
A foot with skin stretched between the toes, which pushes against the water like a paddle.
Grade 4 Life Science: Classification, Lesson 4.2 (grade 4)
well logEnglish
The driller’s record of a well: the depth and kind of each layer passed through, the depth of the hole, where water was found, and the well’s yield.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.3 (grade 8) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.2 (grade 8)
The driller’s record of a well: the depth and kind of each layer passed through, the depth of the hole, where water was found, and the well’s yield.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 8.3 (grade 8) · Grade 8 Earth Science: Earth Resources and Careers, Lesson 9.2 (grade 8)
well screenEnglish
A slotted or mesh section at the bottom of the casing that lets water in while keeping sand and gravel out.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.3 (grade 8)
A slotted or mesh section at the bottom of the casing that lets water in while keeping sand and gravel out.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 2.3 (grade 8)
westEnglish
The side of the sky where the sun goes down every evening.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 5.1 (grade K)
The side of the sky where the sun goes down every evening.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 5.1 (grade K)
wet mountEnglish
A slide on which the specimen sits in a drop of water (or stain) under a coverslip. Used for living things and soft tissue.
Grade 7 Life Science: Cells and Microbes, Lesson 1.3 (grade 7)
A slide on which the specimen sits in a drop of water (or stain) under a coverslip. Used for living things and soft tissue.
Grade 7 Life Science: Cells and Microbes, Lesson 1.3 (grade 7)
whistleEnglish
A longer, tone-like dolphin sound used to communicate with other dolphins, not to echolocate.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.2 (grade 6)
A longer, tone-like dolphin sound used to communicate with other dolphins, not to echolocate.
Grade 6 Life Science: Animal Design and Behavior, Lesson 3.2 (grade 6)
white blood cellEnglish
A blood cell that defends the body against germs. Some swallow germs; others make antibodies that help destroy them.
Grade 5 Life Science: The Human Body, Lesson 3.3 (grade 5)
A blood cell that defends the body against germs. Some swallow germs; others make antibodies that help destroy them.
Grade 5 Life Science: The Human Body, Lesson 3.3 (grade 5)
wildlife biologistEnglish
A scientist who studies wild animals and their habitats: counting, marking and tracking them to learn how many there are, where they go and what they need.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.2 (grade 8)
A scientist who studies wild animals and their habitats: counting, marking and tracking them to learn how many there are, where they go and what they need.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 8.2 (grade 8)
windEnglish
Air that is moving from one place to another.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.1 (grade 1) · Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.3 (grade 1) · Grade 4 Earth Science: Weather and Water, Lesson 2.4 (grade 4) · +3 more
Air that is moving from one place to another.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.1 (grade 1) · Grade 1 Earth Science: Rocks, Water and Weather, Lesson 9.3 (grade 1) · Grade 4 Earth Science: Weather and Water, Lesson 2.4 (grade 4) · +3 more
wind chillEnglish
How cold the air feels on bare skin when wind carries body heat away faster.
Grade 4 Earth Science: Weather and Water, Lesson 4.3 (grade 4)
How cold the air feels on bare skin when wind carries body heat away faster.
Grade 4 Earth Science: Weather and Water, Lesson 4.3 (grade 4)
wind directionEnglish
The direction the wind is blowing from. A north wind blows from the north toward the south.
Grade 3 Life Science: Plants and Animals Together, Lesson 8.3 (grade 3)
The direction the wind is blowing from. A north wind blows from the north toward the south.
Grade 3 Life Science: Plants and Animals Together, Lesson 8.3 (grade 3)
wind shearEnglish
A change in wind speed or direction with height. Shear tilts a storm so its updraft and downdraft do not fight each other, and it can start the updraft rotating.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.2 (grade 8) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 8.4 (grade 6)
A change in wind speed or direction with height. Shear tilts a storm so its updraft and downdraft do not fight each other, and it can start the updraft rotating.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.2 (grade 8) · Grade 6 Geography: Physical Geography: The Earth’s Systems, Lesson 8.4 (grade 6)
wind shear and microburstEnglish
A sudden change of wind speed or direction over a short distance. A microburst is a small, intense downdraft from a thunderstorm that spreads out at the ground and can rob a landing aircraft of airspeed.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.3 (grade 8)
A sudden change of wind speed or direction over a short distance. A microburst is a small, intense downdraft from a thunderstorm that spreads out at the ground and can rob a landing aircraft of airspeed.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 6.3 (grade 8)
wind vaneEnglish
A pointer that turns on a pole. Its point turns to face where the wind is coming from. It is also called a weather vane.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.2 (grade 1) · Grade 4 Earth Science: Weather and Water, Lesson 9.1 (grade 4)
A pointer that turns on a pole. Its point turns to face where the wind is coming from. It is also called a weather vane.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.2 (grade 1) · Grade 4 Earth Science: Weather and Water, Lesson 9.1 (grade 4)
windmillEnglish
A machine with big sails that the wind turns. The turning does work, like grinding grain into flour or pumping water.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.3 (grade 1) · Kindergarten Engineering & Physics, Lesson 9.3 (grade K) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 3.3 (grade 4)
A machine with big sails that the wind turns. The turning does work, like grinding grain into flour or pumping water.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.3 (grade 1) · Kindergarten Engineering & Physics, Lesson 9.3 (grade K) · Grade 4 Geography: The United States: Regions, Rivers and Routes, Lesson 3.3 (grade 4)
windows of heavenEnglish
The second source named in Genesis 7:11: rain from above, which fell for forty days and forty nights.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.4 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 4.1 (grade 7)
The second source named in Genesis 7:11: rain from above, which fell for forty days and forty nights.
Grade 6 Earth Science: The Dynamic Earth, Lesson 7.4 (grade 6) · Grade 7 Earth Science: Earth History and the Flood, Lesson 4.1 (grade 7)
windsockEnglish
A cloth tube on a pole that fills with wind and shows which way the wind is blowing and how strong it is.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.1 (grade 1)
A cloth tube on a pole that fills with wind and shows which way the wind is blowing and how strong it is.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 5.1 (grade 1)
windward sideEnglish
The side of a mountain that faces into the wind. Air is pushed up this side, so it is usually cloudy and wet.
Grade 4 Earth Science: Weather and Water, Lesson 8.2 (grade 4)
The side of a mountain that faces into the wind. Air is pushed up this side, so it is usually cloudy and wet.
Grade 4 Earth Science: Weather and Water, Lesson 8.2 (grade 4)
wing barEnglish
A pale stripe across a bird’s folded wing, made by the light-colored tips of a row of feathers.
Grade 4 Life Science: Classification, Lesson 4.4 (grade 4)
A pale stripe across a bird’s folded wing, made by the light-colored tips of a row of feathers.
Grade 4 Life Science: Classification, Lesson 4.4 (grade 4)
wing coversEnglish
The two hard, shiny halves on a ladybug’s back. They open like doors so the thin wings underneath can fly.
Kindergarten Life Science: God Made the Animals, Lesson 4.3 (grade K)
The two hard, shiny halves on a ladybug’s back. They open like doors so the thin wings underneath can fly.
Kindergarten Life Science: God Made the Animals, Lesson 4.3 (grade K)
winterEnglish
The coldest season of the year, with the shortest days and the longest nights.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.4 (grade K)
The coldest season of the year, with the shortest days and the longest nights.
Kindergarten Earth Science: God Made the Ground and Sky, Lesson 6.4 (grade K)
wintering groundsEnglish
The place where a migrating animal spends the season when it is not breeding. For the Arctic tern, this is the edge of the Antarctic pack ice during the southern summer.
Grade 6 Life Science: Animal Design and Behavior, Lesson 2.1 (grade 6)
The place where a migrating animal spends the season when it is not breeding. For the Arctic tern, this is the edge of the Antarctic pack ice during the southern summer.
Grade 6 Life Science: Animal Design and Behavior, Lesson 2.1 (grade 6)
wiseEnglish
Knowing what is right and good, and choosing to do it.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 2.4 (grade 1)
Knowing what is right and good, and choosing to do it.
Grade 1 Earth Science: Rocks, Water and Weather, Lesson 2.4 (grade 1)
woolly mammothEnglish
An extinct elephant kind (Mammuthus primigenius) with a thick hairy coat, small ears, a fatty hump and long curved tusks, known from bones, tusks, frozen carcasses and cave paintings.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.2 (grade 7) · Explore Dinosaurs · Expert, Stop 5.6 (Ages 14+) · Explore Dinosaurs · Ranger, Stop 5.6 (Ages 10–13) · +1 more
An extinct elephant kind (Mammuthus primigenius) with a thick hairy coat, small ears, a fatty hump and long curved tusks, known from bones, tusks, frozen carcasses and cave paintings.
Grade 7 Earth Science: Earth History and the Flood, Lesson 5.2 (grade 7) · Explore Dinosaurs · Expert, Stop 5.6 (Ages 14+) · Explore Dinosaurs · Ranger, Stop 5.6 (Ages 10–13) · +1 more
worldviewEnglish
The set of beliefs through which a person reads evidence and answers big questions such as “Where did we come from?”
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.1 (grade 8)
The set of beliefs through which a person reads evidence and answers big questions such as “Where did we come from?”
Grade 8 Life Science: Heredity, Design and Origins, Lesson 6.1 (grade 8)
wrack lineEnglish
A wiggly line of seaweed, shells and driftwood left on the beach where the high tide stopped.
Grade 2 Earth Science: The Earth's Surface, Lesson 6.4 (grade 2)
A wiggly line of seaweed, shells and driftwood left on the beach where the high tide stopped.
Grade 2 Earth Science: The Earth's Surface, Lesson 6.4 (grade 2)
X
X-rayEnglish
An invisible kind of light that passes through soft parts of the body more easily than through bone, so it can make pictures of bones.
Grade 5 Life Science: The Human Body, Lesson 2.3 (grade 5) · Grade 1 Physical Education & Health, Lesson 4.1 (grade 1)
An invisible kind of light that passes through soft parts of the body more easily than through bone, so it can make pictures of bones.
Grade 5 Life Science: The Human Body, Lesson 2.3 (grade 5) · Grade 1 Physical Education & Health, Lesson 4.1 (grade 1)
X-ray diffractionEnglish
A way of studying the arrangement of atoms by shining X-rays through a crystal or fiber and recording the pattern of spots the scattered rays make on film.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.1 (grade 8)
A way of studying the arrangement of atoms by shining X-rays through a crystal or fiber and recording the pattern of spots the scattered rays make on film.
Grade 8 Life Science: Heredity, Design and Origins, Lesson 2.1 (grade 8)
Y
young-earth creationEnglish
The view that God created the heavens and the earth in six ordinary days a few thousand years ago, as the plain reading of Genesis 1 and the genealogies of Genesis 5 and 11 suggest.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.1 (grade 8)
The view that God created the heavens and the earth in six ordinary days a few thousand years ago, as the plain reading of Genesis 1 and the genealogies of Genesis 5 and 11 suggest.
Grade 8 Earth Science: Earth Resources and Careers, Lesson 7.1 (grade 8)
Z
zenithEnglish
The point in the sky straight above your head, at an altitude of 90°.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.2 (grade 5)
The point in the sky straight above your head, at an altitude of 90°.
Grade 5 Earth Science: The Sky: Sun, Moon and Stars, Lesson 8.2 (grade 5)
zirconEnglish
A hard, durable mineral that takes in uranium when it crystallizes but very little lead, which is why geologists prefer it for uranium-lead dating.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.2 (grade 7)
A hard, durable mineral that takes in uranium when it crystallizes but very little lead, which is why geologists prefer it for uranium-lead dating.
Grade 7 Earth Science: Earth History and the Flood, Lesson 7.2 (grade 7)
zone of inhibitionEnglish
The clear ring around a substance on a culture plate where microbes could not grow. A wider zone means a stronger effect.
Grade 7 Life Science: Cells and Microbes, Lesson 4.3 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.3 (grade 8)
The clear ring around a substance on a culture plate where microbes could not grow. A wider zone means a stronger effect.
Grade 7 Life Science: Cells and Microbes, Lesson 4.3 (grade 7) · Grade 8 Life Science: Heredity, Design and Origins, Lesson 3.3 (grade 8)
zooEnglish
A park where wild animals are kept and cared for so people can see them and learn about them.
Grade 1 Life Science: Animal Homes and Habits, Lesson 9.3 (grade 1) · Grade 2 Life Science: Animal Families, Lesson 9.3 (grade 2) · Grade 4 Life Science: Classification, Lesson 9.3 (grade 4) · +1 more
A park where wild animals are kept and cared for so people can see them and learn about them.
Grade 1 Life Science: Animal Homes and Habits, Lesson 9.3 (grade 1) · Grade 2 Life Science: Animal Families, Lesson 9.3 (grade 2) · Grade 4 Life Science: Classification, Lesson 9.3 (grade 4) · +1 more