How can you count all to add 6 + 3?

Count 1, 2, 3, 4, 5, 6, 7, 8, 9. So 6 + 3 = 9.

How can you count on to add 4 + 2?

Start at 4. Then count on 2 more: 5, 6. So 4 + 2 = 6. Or, start at 2. Then count on 4 more. 3, 4, 5, 6. So 4 + 2 = 6.

How can you count back to subtract 7 – 5?

Start at 7. Then count back 5: 6, 5, 4, 3, 2. So 7 – 5 = 2.

How can you count on to subtract 9 – 7?

Start at 7. Then count on to 9. 8, 9. I counted 2, so 9 – 7 = 2.

There are 6 dogs at a park. 2 more dogs arrive. How many dogs are there in all?

6 + 2 = 8. There are 8 dogs in all.

How can you add 5 + 9?

You could count all, count on from 5, or count on from 9. 5 + 9 = 14.

In an addition problem like 9 + ? = 12, how can you find the missing number?

I can count on to find the missing number. Start at 9 and count on to 12. I put up one finger for each number I count. 10, 11, 12. I put up 3 fingers, which means I counted on 3. So, the missing number is 3.

How can you subtract 15 – 3?

I could count back from 15 or count on from 3. 15 – 3 = 12.

In a subtraction problem like 19 – ? = 14, how can you find the missing number?

I can count back to find the missing number. Start at 19 and count back to 14. To keep track on my fingers, I put up one finger for each number I count. 18, 17, 16, 15, 14. I put up 5 fingers, so I counted back 5. So, the missing number is 5.

You have 14 stickers. You give some away. You have 9 left. How many stickers did you give away?

14 – ? = 9. Start from 14. Then, count back to 9. 13, 12, 11, 10, 9. I counted back 5 numbers, so the missing number is 5. I gave away 5 stickers.

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Add & Subtract Within 20

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What you will learn from this videoWhat you will learn

We’ll learn how to add and subtract numbers up to 20.
We'll also learn how to solve addition and subtraction problems with a missing number.
And we’ll discover that this knowledge can help us win trophies, feed animals, and even decorate gingerbread houses!

Discussion Questions
- Before Video
  How can you count all to add 6 + 3?ANSWER
  - Count 1, 2, 3, 4, 5, 6, 7, 8, 9. So 6 + 3 = 9.
  How can you count on to add 4 + 2?ANSWER
  - Start at 4. Then count on 2 more: 5, 6. So 4 + 2 = 6. Or, start at 2. Then count on 4 more. 3, 4, 5, 6. So 4 + 2 = 6.
  How can you count back to subtract 7 – 5?ANSWER
  - Start at 7. Then count back 5: 6, 5, 4, 3, 2. So 7 – 5 = 2.
  How can you count on to subtract 9 – 7?ANSWER
  - Start at 7. Then count on to 9. 8, 9. I counted 2, so 9 – 7 = 2.
  There are 6 dogs at a park. 2 more dogs arrive. How many dogs are there in all?ANSWER
  - 6 + 2 = 8. There are 8 dogs in all.
- After Video
  How can you add 5 + 9?ANSWER
  - You could count all, count on from 5, or count on from 9. 5 + 9 = 14.
  In an addition problem like 9 + ? = 12, how can you find the missing number?ANSWER
  - I can count on to find the missing number. Start at 9 and count on to 12. I put up one finger for each number I count. 10, 11, 12. I put up 3 fingers, which means I counted on 3. So, the missing number is 3.
  How can you subtract 15 – 3?ANSWER
  - I could count back from 15 or count on from 3. 15 – 3 = 12.
  In a subtraction problem like 19 – ? = 14, how can you find the missing number?ANSWER
  - I can count back to find the missing number. Start at 19 and count back to 14. To keep track on my fingers, I put up one finger for each number I count. 18, 17, 16, 15, 14. I put up 5 fingers, so I counted back 5. So, the missing number is 5.
  You have 14 stickers. You give some away. You have 9 left. How many stickers did you give away?ANSWER
  - 14 – ? = 9. Start from 14. Then, count back to 9. 13, 12, 11, 10, 9. I counted back 5 numbers, so the missing number is 5. I gave away 5 stickers.
Vocabulary
- Add DEFINE
- Subtract DEFINE
- Count all DEFINE
- Count on DEFINE
- Count back DEFINE
- Difference DEFINE
- Sum DEFINE

Reading Material
Practice Word Problems
Practice Number Problems
Lesson Plan
Teacher Guide
Assessment
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Add & Subtract Within 20

Discussion Questions

Vocabulary

Reading Material

Practice Word Problems

Practice Number Problems

Lesson Plan

Teacher Guide

Assessment