Math lesson plan · 1st grade (Year 2 in England) · 45 minutes
Add within 20
Addition and subtraction
CCSS 1.OA.C.6CCSS 1.OA.A.1England: Y1 Addition and subtraction
Objective and success criteria
Students will: Add within 20.
- 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 within 10; Make 10 (number bonds); Teen numbers: ten and some ones
Leads to: Subtract within 20; Missing numbers and the equal sign; Add and subtract tens
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 within 10; Make 10 (number bonds); Teen numbers: ten and some ones). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
Hook · 5 min
- Give a real shopping total or a score difference and ask for a quick estimate first.
- Share the objective: Add within 20. 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: Kai has 9 cookies. A friend gives Kai 4 more. How many cookies does Kai have now?
- Step 1: 9 + 4 = 13
- Answer: 13
- 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.
- There are 10 shells in a box and 7 on the table. How many shells are there in all? → 17Prompt: Do we join the groups or take away?
- 6 + 6 + 5 = ? → 17Prompt: You can add three numbers in any order.
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.
- Zara has 9 stickers. A friend gives Zara 10 more. How many stickers does Zara have now? → 19Prompt: Do we join the groups or take away?
- 4 + 6 + 2 = ? → 12Prompt: You can add three numbers in any order.
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 within 10.
- 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: Subtract within 20; Missing numbers and the equal sign; Add and subtract tens.
- 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