Parent guide · Grade 3 Math · Unit 8

Lesson 8.3 Right Angles and Quadrilaterals

Written for the parent. Read the Say this lines aloud as they are, or in your own words. Answers for you are marked Listen for.

At a glance

Time: 5 sessions of 25–30 minutes
Goal: Find right angles. Name and sort quadrilaterals.
You need: Pencil and crayons
Print: Worksheet A · Worksheet B · the lesson page (it also has a short video (9:49))

Steps

Warm-up
Do this: Ask these out loud. Your child answers out loud; no paper needed.
- Ask: “5 × 2” Listen for: 10
- Ask: “5 × 8” Listen for: 40
- Ask: “7 × 10” Listen for: 70
- Ask: “2 × 9” Listen for: 18
- Ask: “10 × 4” Listen for: 40
Teach the new idea
Say this: “Fold a scrap of paper twice to make a right-angle tester. Smaller than the tester is acute; bigger is obtuse.”
Say this: “A square is a rectangle and a rhombus at the same time. Sort by sides and angles.”
Say this: “Right angle: a square corner.”
Say this: “Quadrilateral: a shape with 4 straight sides.”
Say this: “Parallel: always the same distance apart.”
Say this: “Rhombus: 4 equal sides.”
Show how
Show: A quadrilateral has exactly one pair of parallel sides. What is its most exact name?
Say this: “Exactly one pair of parallel sides: that is a trapezoid.”
Answer: trapezoid
Show: Find the perimeter of a rectangle 3 in long and 7 in wide.
$rectangle$
Say this: “Add all four sides: 3 + 7 + 3 + 7 = 20”
Say this: “Perimeter = 20 in”
Answer: 20 in
Practice together
Do this: Your child does these with you. Let them try first; help only after a real try.
Ask: Is this angle acute, right or obtuse?
$angle$
Listen for: obtuse
If stuck: A right angle is a square corner, 90°.
Ask: Is this angle acute, right or obtuse?
$angle$
Listen for: acute
If stuck: A right angle is a square corner, 90°.
Ask: Is this angle acute, right or obtuse?
$angle$
Listen for: acute
If stuck: A right angle is a square corner, 90°.
10 more practice items on the lesson page, and on Worksheet A and Worksheet B.
Watch for
- Saying a square is not a rectangle.
Game: Kitchen Scale
Weigh five kitchen items in grams. Order them lightest to heaviest. Estimate first, then weigh.
Narration
Say this: “Tell me what you learned today. Show me with your hands or the counters if you like.”
Listen for: Find right angles.; Name and sort quadrilaterals.
Daily habit
Fact drill. Recite: 60 minutes = 1 hour, 1,000 grams = 1 kilogram, 1,000 milliliters = 1 liter.

Spread over the week

5 sessions of 25–30 minutes. Stop while it is still going well.

Session 1. Warm-up, then teach the new idea (steps 1 and 2).
Session 2. Warm-up again, then show how with the examples.
Session 3. Practice together, then play the game.
Session 4. More practice on the worksheet, and the daily habit.
Session 5. Quick check: narration and a few practice items. Move on when it is mostly right.