Addition and subtraction word problems within 20 (grade 1) · lesson

What happens at the end

+

Tap each one to count it

💡 When you know the start and the change, find the end.

Kai has 7 shells. He finds 5 more. Add: 7 + 5 = 12.

16 apples. The class eats 9. Take away: 16 − 9 = 7.

🧠 How to think about it

Ask: did the group get bigger or smaller? Bigger means add. Smaller means take away.

story problem: a math question told as a story

🏡 Try it at home

Tell a snack story: "You have 6 grapes. I give you 4 more." How many now?

How many came?

💡 If you know the start and end, find the change.

8 birds. Some more come. Now there are 13.

Count up from 8 to 13. That is 5. So 5 birds came.

🧠 How to think about it

Write 8 + ? = 13. Count up from 8: 9, 10, 11, 12, 13. Five counts. ? is 5.

unknown: the number we need to find

🏡 Try it at home

Put 5 toys out. Add some while your child looks away. Ask how many you added.

How many at first?

💡 When the start is missing, work back from the end.

Some cars were parked. 6 more came. Now there are 14.

Take away the 6 that came. 14 − 6 = 8. So 8 were there first.

🧠 How to think about it

10 kids are left. 5 went home. Put the 5 back: 10 + 5 = 15 kids at first.

at first: at the start

🏡 Try it at home

Hide some coins in a cup. Add 3 more on top. Count all. How many were hidden?

How many more or fewer

💡 To find how many more or fewer, find the difference.

Lily has 9 stars. Sam has 6. Line them up.

Lily has 3 with no match. So she has 3 more. 9 − 6 = 3.

🧠 How to think about it

"How many more" does not mean add. Line them up and count the extras.

more than: how many extra
fewer than: how many less

🏡 Try it at home

Line up your shoes and a grown-up's shoes. Who has more? How many more?

Adding three numbers

+

Tap each one to count it

💡 To add three numbers, look for two that make 10 first.

3 + 7 + 3. First, 3 + 7 = 10. Then 10 + 3 = 13.

You can add in any order. Pick the easy pair.

🧠 How to think about it

4 + 5 + 6: 4 and 6 make 10. Then add 5. 10 + 5 = 15.

pair: two numbers that go together

🏡 Try it at home

Roll three dice. Look for a pair that makes 10, or close. Add all three.

Match the story to a number sentence

💡 A number sentence with a ? shows which part of the story is missing.

Mia had 12 grapes. She ate some. Now she has 7.

That is 12 − ? = 7. The ? is how many she ate.

🧠 How to think about it

Put the story's numbers in order: start, change, end. Use + for more, − for less. Put ? where the number is missing.

equation: a number sentence with an equal sign

🏡 Try it at home

Tell a story with a missing part. Write it with a ? together, like 5 + ? = 8.