Math lesson plan · 2nd grade (Year 3 in England) · 45 minutes
Find the missing number in additions and subtractions to 100
Addition and subtraction
CCSS 2.OA.A.1CCSS 2.NBT.B.5England: Y2 Addition and subtractionEngland: Y3 Addition and subtraction
Objective and success criteria
Students will: Find the missing number in additions and subtractions to 100.
- 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: Missing numbers and the equal sign; Find a difference by counting up
Leads to: Story problems: work out the starting amount
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 (Missing numbers and the equal sign; Find a difference by counting up). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- 9 + 9 = 2 + __ → 16Prompt: The equal sign means both sides have the same value.
- True or false? 4 + 4 = 10 (True / False) → FalsePrompt: Work out the value of each side.
- __ + 7 = 20 → 13Prompt: What do you add to 7 to make 20?
Hook · 5 min
- Give a real shopping total or a score difference and ask for a quick estimate first.
- Share the objective: Find the missing number in additions and subtractions to 100. 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: 35 + __ = 78
- Step 1: 78 − 35 = 43
- Step 2: 43
- Answer: 43
- 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.
- 17 + __ = 30 → 13Prompt: Count up from 17 to 30.
- 51 − __ = 33 → 18Prompt: How much was taken away?
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.
- 27 + __ = 89 → 62Prompt: Count up from 27 to 89.
- 54 − __ = 31 → 23Prompt: How much was taken away?
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: Missing numbers and the equal sign.
- 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: Story problems: work out the starting amount.
- 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