Math lesson plan · 2nd grade (Year 3 in England) · 60 minutes
Add three-digit numbers without regrouping
Addition and subtraction
CCSS 2.NBT.B.7England: Y3 Addition and subtraction
Objective and success criteria
Students will: Add three-digit numbers without 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 whole hundreds; Add two-digit numbers without regrouping
Leads to: Add three-digit numbers with regrouping
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 (Add and subtract whole hundreds; Add two-digit numbers without regrouping). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- 400 + 100 = ? → 500Prompt: Think in hundreds: 4 + 1.
- 521 − 100 = ? → 421Prompt: Only the hundreds digit changes.
- 700 + 100 = ? → 800Prompt: Think in hundreds: 7 + 1.
Hook · 6 min
- Give a real shopping total or a score difference and ask for a quick estimate first.
- Share the objective: Add three-digit numbers without 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: Hana has 515 beads. Kwame has 384 more beads than Hana. How many beads does Kwame have?
- Step 1: 515 + 384 = 899
- Step 2: 899
- Answer: 899
- 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.
- Chloe has 160 acorns. Omar has 313 more acorns than Chloe. How many acorns does Omar have? → 473Prompt: Who has more, Chloe or Omar?
- There are 235 stickers on the table and 641 stickers in a box. How many stickers are there altogether? → 876Prompt: Altogether means put both groups together.
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.
- Zoe has 512 stones. Grace has 306 more stones than Zoe. How many stones does Grace have? → 818Prompt: Who has more, Zoe or Grace?
- There are 512 photos on the table and 332 photos in a box. How many photos are there altogether? → 844Prompt: Altogether means put both groups together.
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 whole hundreds.
- 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 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