Math lesson plan · 2nd grade (Year 3 in England) · 45 minutes
Subtract two-digit numbers with regrouping
Addition and subtraction
CCSS 2.NBT.B.5England: Y2 Addition and subtractionEngland: Y3 Addition and subtraction
Objective and success criteria
Students will: Subtract two-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: Add two-digit numbers with regrouping; Subtract within 20
Leads to: Add and subtract within 1000; Two-step addition and subtraction problems; Subtract three-digit numbers with regrouping
Materials: Base-ten blocks, Number lines, Hundred square, Mini whiteboards and pens, Printed student sheet (below).
Warm-up · 5 min
- Quick retrieval from earlier learning (Add two-digit numbers with regrouping; Subtract within 20). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- Grace collected 21 cookies in the morning and 72 in the afternoon. How many is that altogether? → 93Prompt: Add the tens, then add the ones.
- Luis collected 35 crayons in the morning and 62 in the afternoon. How many is that altogether? → 97Prompt: Add the tens, then add the ones.
- There are 45 cookies in a box and 49 on the table. How many cookies are there in all? → 94Prompt: Add the tens, then add the ones.
Hook · 5 min
- Give a real shopping total or a score difference and ask for a quick estimate first.
- Share the objective: Subtract two-digit numbers with regrouping. Read the success criteria together.
I do: model it · 10 min
- Work through the example out loud, saying why you do each step, not just what you do.
- Example: Grace has 85 apples. Zoe has 37. How many more apples does Grace have than Zoe?
- Step 1: 85 − 37 = 48
- Answer: 48
- Pause after each step and ask a student to say what comes next.
We do: guided practice · 10 min
- Do these together. Students try each step on whiteboards before you reveal it.
- Use the hints as prompts rather than giving the answer.
- Ethan had 86 apples and gave away 59. How many apples are left? → 27Prompt: This is a subtraction problem. Which number is the whole?
- 80 − 49 = ? → 31Prompt: There are 0 ones, so regroup a ten.
You do: independent practice · 10 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 · 5 min
- Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
- There were 60 shells. Then 15 were used. How many are left? → 45Prompt: This is a subtraction problem. Which number is the whole?
- 80 − 35 = ? → 45Prompt: There are 0 ones, so regroup a ten.
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: Add two-digit numbers with 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
- Move on to: Add and subtract within 1000; Two-step addition and subtraction problems; Subtract three-digit numbers with regrouping.
- 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