Parent guide · Grade 2 Math · Unit 5
Lesson 5.1 Adding Three-Digit Numbers
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 20–25 minutes
- Goal
- Add three-digit numbers with the written method.
- You need
- Pencil and crayons
- A King James Bible
- Worksheet A · Worksheet B · the lesson page
Steps
Do this: Ask these out loud. Your child answers out loud; no paper needed.
- Ask: “What number is ten more than 382?” Listen for: 392
- Ask: “What number is ten less than 699?” Listen for: 689
- Ask: “What number is ten less than 385?” Listen for: 375
- Ask: “What number is ten more than 527?” Listen for: 537
- Ask: “What number is ten more than 884?” Listen for: 894
Say this: “The same steps work for bigger numbers: ones, then tens, then hundreds.”
Say this: “Ten tens regroup to one hundred.”
Say this: “Hundreds: the third column from the right.”
Show: 454 + 374 = ___
Say this: “Ones: 4 + 4 = 8. Write 8.”
Say this: “Tens: 5 + 7 = 12. Write 2 and regroup 1 to the hundreds.”
Say this: “Hundreds: 1 + 4 + 3 = 8. Write 8.”
Say this: “454 + 374 = 828”
Answer: 828
Show: There are 419 ducks on the pond and 286 more fly in. How many ducks are on the pond now?
Say this: “Unknown: the total.”
Say this: “Bar model: two parts, 419 and 286; the whole is unknown.”
Say this: “Equation: 419 + 286 = ?”
Say this: “419 + 286 = 705”
Say this: “Answer: There are 705 ducks now.”
Answer: 705 ducks. There are 705 ducks now.
Do this: Your child does these with you. Let them try first; help only after a real try.
Ask: 313 + 213 = ___
Listen for: 526
If stuck: Ones: 3 + 3 = 6. Write 6.
Ask: 116 + 351 = ___
Listen for: 467
If stuck: Ones: 6 + 1 = 7. Write 7.
Ask: 130 + 165 = ___
Listen for: 295
If stuck: Ones: 0 + 5 = 5. Write 5.
7 more practice items on the lesson page, and on Worksheet A and Worksheet B.
- Forgetting a regrouped 1 in the hundreds.
Price a few household items between 100 and 500 cents. Your child adds two prices on paper and checks with a partner. Then find how much more one costs than the other.
Say this: “Tell me what you learned today. Show me with your hands or the counters if you like.”
Listen for: Add three-digit numbers with the written method.
So the wall was finished in the twenty and fifth day of the month Elul, in fifty and two days.
Fifty-two days of steady work finished a great wall. Big jobs are made of small steps.
Count by tens and hundreds from any number, forward and back.
Spread over the week
5 sessions of 20–25 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.