Lesson 2.1 Adding with Regrouping

Steps

1. Warm-up

   Do this: Ask these out loud. Your child answers out loud; no paper needed.

   • Ask: “500 + 400” Listen for: 900
   • Ask: “800 + 300” Listen for: 1,100
   • Ask: “600 + 100” Listen for: 700
   • Ask: “100 + 100” Listen for: 200
   • Ask: “700 + 200” Listen for: 900
2. Teach the new idea

   Say this: “Line up the places. Add ones, tens, hundreds, thousands, regrouping whenever a column makes 10 or more.”

   Say this: “Estimate first so you know about how big the answer should be.”

   Say this: “Regroup: trade 10 of one place for 1 of the next.”

3. Show how

   Show: 1,781 + 4,746 = ___

   Say this: “Ones: 1 + 6 = 7. Write 7.”

   Say this: “Tens: 8 + 4 = 12. Write 2 and regroup 1 to the hundreds.”

   Say this: “Hundreds: 1 + 7 + 7 = 15. Write 5 and regroup 1 to the thousands.”

   Say this: “Thousands: 1 + 1 + 4 = 6. Write 6.”

   Say this: “1,781 + 4,746 = 6,527”

   Answer: 6,527

   Show: A carpenter cut 2,109 boards on Monday and 4,324 boards on Tuesday. How many boards did he cut?

   

   Say this: “Unknown: the total.”

   Say this: “Bar model: two parts, 2,109 and 4,324; the whole is unknown.”

   Say this: “Equation: 2,109 + 4,324 = ?”

   Say this: “2,109 + 4,324 = 6,433”

   Say this: “Answer: He cut 6,433 boards.”

   Answer: 6,433 boards. He cut 6,433 boards.

4. Practice together

   Do this: Your child does these with you. Let them try first; help only after a real try.

   Ask: 369 + 235 = ___

   Listen for: 604

   If stuck: Ones: 9 + 5 = 14. Write 4 and regroup 1 to the tens.

   Ask: 307 + 421 = ___

   Listen for: 728

   If stuck: Ones: 7 + 1 = 8. Write 8.

   Ask: 128 + 696 = ___

   Listen for: 824

   If stuck: Ones: 8 + 6 = 14. Write 4 and regroup 1 to the tens.

   7 more practice items on the lesson page, and on Worksheet A and Worksheet B.

5. Watch for
   • Misaligned columns when the numbers have different numbers of digits.
6. Game: Cross Check

   One player adds two 3-digit numbers on paper while the other estimates. Compare: is the exact answer close to the estimate? Swap roles.

7. Narration

   Say this: “Tell me what you learned today. Show me with your hands or the counters if you like.”

   Listen for: Add three- and four-digit numbers with the written method.

8. Scripture

   Then they that gladly received his word were baptized: and the same day there were added unto them about three thousand souls.

   On the day of Pentecost about three thousand were added to the church.

9. Daily habit

   Mental math warm-up: add or subtract 10, 100 or 1,000.

Spread over the week

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

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