Math lesson plan · 1st grade (Year 2 in England) · 45 minutes
Add tens to a two-digit number
Addition and subtraction
CCSS 1.NBT.C.4England: Y1 Addition and subtractionEngland: Y2 Addition and subtraction
Objective and success criteria
Students will: Add tens to a two-digit number.
- 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 tens; Find 10 more and 10 less
Leads to: Add two-digit numbers without regrouping; Find a difference by counting up; Add and subtract with jumps on an open number line
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 tens; Find 10 more and 10 less). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- 10 + 60 = ? → 70Prompt: Think in tens: 1 tens and 6 tens.
- 40 + 40 = ? → 80Prompt: Think in tens: 4 tens and 4 tens.
- 50 − 20 = ? → 30Prompt: Think in tens: 5 tens take away 2 tens.
Hook · 5 min
- Give a real shopping total or a score difference and ask for a quick estimate first.
- Share the objective: Add tens to a two-digit number. 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: 19 + __ = 79
- Step 1: 79 − 19 = 60
- Step 2: 60
- Answer: 60
- 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.
- 51 + __ = 91 → 40Prompt: Which digit changed?
- 39 + __ = 59 → 20Prompt: Which digit changed?
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.
- 35 + __ = 75 → 40Prompt: Which digit changed?
- 46 + __ = 86 → 40Prompt: Which digit changed?
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 tens.
- 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 two-digit numbers without regrouping; Find a difference by counting up; Add and subtract with jumps on an open number line.
- 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-1.
Free lesson plan from eurekami.com/lesson-plan-builder