Math lesson plan · 2nd grade (Year 3 in England) · 45 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 · 5 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.
- 100 + 100 = ? → 200Prompt: Think in hundreds: 1 + 1.
- 204 − 100 = ? → 104Prompt: Only the hundreds digit changes.
- 300 + 600 = ? → 900Prompt: Think in hundreds: 3 + 6.
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 without 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: 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 · 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.
- Isla has 446 acorns. Chloe has 101 more acorns than Isla. How many acorns does Chloe have? → 547Prompt: Who has more, Isla or Chloe?
- Amara has 388 seeds. Leo has 410 more seeds than Amara. How many seeds does Leo have? → 798Prompt: Who has more, Amara or Leo?
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 are 420 beads on the table and 171 beads in a box. How many beads are there altogether? → 591Prompt: Altogether means put both groups together.
- Kofi has 238 stickers. Ana has 431 more stickers than Kofi. How many stickers does Ana have? → 669Prompt: Who has more, Kofi or Ana?
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