Math lesson plan · 3rd grade (Year 4 in England) · 45 minutes
Add three-digit numbers with regrouping
Addition and subtraction
CCSS 3.NBT.A.2England: Y3 Addition and subtraction
Objective and success criteria
Students will: Add 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: Add and subtract within 1000
Leads to: Add four-digit numbers in columns; Find missing digits in column sums; Check answers with the inverse operation
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 and subtract within 1000). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- What is 10 more than 392? → 402Prompt: Which digit changes when you add 10?
- 812 − 145 = ? → 667Prompt: Line up hundreds, tens and ones.
- What is 100 more than 784? → 884Prompt: Which digit changes when you add 100?
Hook · 5 min
- Give a real shopping total or a score difference and ask for a quick estimate first.
- Share the objective: Add three-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: 256 + 351 = ?
- Step 1: ones: 6 + 1 = 7
- Step 2: tens: 5 + 5 = 10, carry 1
- Step 3: hundreds: 2 + 3 + 1 = 6
- Step 4: 256 + 351 = 607
- Answer: 607
- 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.
- 139 + 342 = ? → 481Prompt: Add the ones first.
- Luis's school collected 466 cans for recycling in March and 198 in April. How many cans is that altogether? → 664Prompt: Altogether means add.
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.
- Leo added 227 + 317 and got 534. Leo forgot to carry. What is the correct total? → 544Prompt: Check each column: did any make 10 or more?
- Kofi's school collected 458 cans for recycling in March and 463 in April. How many cans is that altogether? → 921Prompt: Altogether means add.
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 and subtract within 1000.
- 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 four-digit numbers in columns; Find missing digits in column sums; Check answers with the inverse operation.
- 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-3.
Free lesson plan from eurekami.com/lesson-plan-builder