Math lesson plan · 2nd grade (Year 3 in England) · 60 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 · 6 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.
- 686 − 134 = ? → 552Prompt: Subtract hundreds, tens and ones separately.
- Noah had 515 beads. Noah gave 212 to Sam. How many beads does Noah have left? → 303Prompt: Noah gives some away, so the amount gets smaller.
- 688 − 334 = ? → 354Prompt: Subtract hundreds, tens and ones separately.
Hook · 6 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 · 12 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 · 12 min
- Do these together. Students try each step on whiteboards before you reveal it.
- Use the hints as prompts rather than giving the answer.
- 848 − 372 = ? → 476Prompt: Start with the ones. If the top digit is smaller, exchange a ten for 10 ones.
- 600 − 105 = ? → 495Prompt: There are 0 tens to exchange from. Exchange a hundred for 10 tens first.
You do: independent practice · 17 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 8 questions are on the student sheet below, with answers in the key.
Exit ticket · 7 min
- Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
- Hana had 750 pencils. Hana gave 411 to Kai. How many pencils does Hana have left? → 339Prompt: Hana gives some away, so the amount gets smaller.
- 800 − 508 = ? → 292Prompt: There are 0 tens to exchange from. Exchange a hundred for 10 tens first.
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