Math lesson plan · 2nd grade (Year 3 in England) · 30 minutes
Subtract three-digit numbers with regrouping
Addition and subtraction
CCSS 2.NBT.B.7CCSS 2.NBT.B.9England: Y3 Addition and subtraction
Objective and success criteria
Students will: Subtract three-digit numbers with regrouping.
- I can answer questions on today's skill on my own, without help.
- I can explain each step and say why it works.
- I can check my answer and spot a mistake.
Before and after
Needs first: Subtract three-digit numbers without regrouping; Subtract two-digit numbers with regrouping
Leads to: the next skill in this area.
Materials: Base-ten blocks, Number lines, Hundred square, Mini whiteboards and pens, Printed student sheet (below).
Warm-up · 4 min
- Quick retrieval from earlier learning (Subtract three-digit numbers without regrouping; Subtract two-digit numbers with regrouping). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- 543 − 102 = ? → 441Prompt: Subtract hundreds, tens and ones separately.
- Isla had 588 shells. Isla gave 211 to Ravi. How many shells does Isla have left? → 377Prompt: Isla gives some away, so the amount gets smaller.
- 385 − 205 = ? → 180Prompt: Subtract hundreds, tens and ones separately.
Hook · 3 min
- Give a real shopping total or a score difference and ask for a quick estimate first.
- Share the objective: Subtract three-digit numbers with regrouping. Read the success criteria together.
I do: model it · 7 min
- Work through the example out loud, saying why you do each step, not just what you do.
- Example: 426 − 282 = ?
- Step 1: Ones: 6 − 2 = 4
- Step 2: Tens: 2 is less than 8, so exchange 1 hundred for 10 tens.
- Step 3: Tens: 12 − 8 = 4
- Step 4: Hundreds: 3 − 2 = 1
- Step 5: 426 − 282 = 144
- Answer: 144
- Pause after each step and ask a student to say what comes next.
We do: guided practice · 6 min
- Do these together. Students try each step on whiteboards before you reveal it.
- Use the hints as prompts rather than giving the answer.
- 662 − 406 = ? → 256Prompt: Start with the ones. If the top digit is smaller, exchange a ten for 10 ones.
- 801 − 731 = ? → 70Prompt: There are 0 tens to exchange from. Exchange a hundred for 10 tens first.
You do: independent practice · 7 min
- Students work on the student sheet. Circulate and check the first two answers of every student early.
- Students who finish: write a question of their own for a partner, with the answer.
The 6 questions are on the student sheet below, with answers in the key.
Exit ticket · 3 min
- Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
- Kofi has 704 crayons. Mei has 548 crayons. How many more crayons does Kofi have than Mei? → 156Prompt: 'How many more' asks for the difference.
- 919 − 720 = ? → 199Prompt: Start with the ones. If the top digit is smaller, exchange a ten for 10 ones.
Watch out for
- Subtracting the smaller digit from the bigger one in every column (52 − 17 = 45).
- Forgetting to add the regrouped (carried) ten.
Support and stretch
Support
- Review first: Subtract three-digit numbers without regrouping.
- Use concrete materials: base-ten blocks.
- Give the first step of each question, or a partly worked example to finish.
- Pair with a confident partner for the guided practice.
Stretch
- Explain a common mistake in writing and how to fix it.
- Write a word problem that uses today's skill, then solve a partner's.
Homework and more practice
Free online practice with hints and printable worksheets for this skill: eurekami.com/math/grade-2.
Free lesson plan from eurekami.com/lesson-plan-builder