Add & Subtract Within 20

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

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.

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

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

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

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

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.

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

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.

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.