Year 1 Adding and Subtracting within 20: check-up and quiz

Key words. A number bond is two numbers that make a total. The whole is the total. The parts make the whole.

Method. Start from the whole. Take away the part you know to find the missing part.

1. Find the whole and the part you know. The whole is the big number at the top of the picture.
   Whole: 14. Part I know: 6.
2. Take the part you know away from the whole. Subtracting finds the missing part.
   14 − 6 = 8
3. Write the missing part.
   8

Check. Check: 6 + 8 = 14. ✓

Watch out. Start from the whole, not from the small number. Do not add the two parts together.

Key words. To make 10 is to fill up to 10 first, then add the rest.

Method. Fill the first ten frame to make 10. Then add what is left over.

1. Put 8 counters on the first ten frame. We need 10 counters to make a full frame.
   8 counters
2. Add 2 more to make 10. 8 needs 2 more to make 10.
   8 + 2 = 10
3. Use the rest of the 6. 6 − 2 = 4, so 4 counters are left over.
   10 + 4 = 14
4. Write the answer.
   14

Check. Check: start at 6 and count on 8. You also reach 14. ✓

Watch out. Fill the frame up to 10 first. Do not forget to take the counters you used from the second number.

Key words. A double is two equal amounts, or a number added to itself.

Method. A double is a number added to itself. Double 7 is 7 + 7.

1. Make two rows of 7. Both rows are the same, so the two numbers are equal.
   7 and 7
2. Count all the things. Count one row, then count the other row.
   7 + 7 = 14
3. Write the answer.
   14

Check. Take one row away: 14 − 7 = 7. One row is left. ✓

Watch out. A double has two equal rows. Do not forget to count the second row.

Key words. A near double is one more or one less than a double.

Method. A near double is one more or one less than a double. Double 8 first, then add one more.

1. Find the double of 8. Double 8 is 8 + 8, two equal groups.
   8 + 8 = 16
2. Add the extra one to 16. 9 is one more than 8, so we add one more.
   16 + 1 = 17
3. Write the answer.
   17

Check. Check: start at 9 and count on 8. You also reach 17. ✓

Watch out. Do not forget the extra one. The answer is one more than the double.

Key words. To count on is to keep going up from a number, one at a time.

Method. Start with the bigger number, 15. Then count on 3.

1. Start at 15. Start with the bigger number. You do not need to start at 1.
   Start: 15
2. Count on 3 more. Say each number as you move one step on.
   16, 17, 18
3. Write the answer. The last number you say is the answer.
   18

Check. Count back 3 from 18. You reach 15 again. ✓

Watch out. Count on from 15. Do not say 15 again as the first step.

Key words. Zero means none at all. We write it as 0.

Method. Zero means none. Adding zero, or taking away zero, changes nothing.

1. Look at the sum: 12 + 0. Find the zero in the sum.
   12 + 0
2. Nothing is added or taken away. The number stays the same as it was.
   12 stays 12
3. Write the answer.
   12

Check. Count 12 things and take away none. You still have 12. ✓

Watch out. Zero does not change a number. Do not write 0 as the answer.

Key words. To take away is to remove some. To count back is to go down one at a time.

Method. Take away 5 from 17 by counting back 5 steps.

1. Start at 17. Start with the whole amount.
   Start: 17
2. Count back 5. Each step back is one less.
   16, 15, 14, 13, 12
3. Write the answer. The last number you say is what is left.
   12

Check. Check: 12 + 5 = 17. ✓

Watch out. Count back, not on. Do not say the starting number as one of the steps.

Key words. The difference is how many more one number is than the other.

Method. The difference is how many more. Take the smaller number from the bigger number.

1. Count the first group: 16 apples. Touch each one once.
   16 apples
2. Count the second group: 11 stars. Touch each one once.
   11 stars
3. Take the smaller number from the bigger number. Subtraction finds how many more.
   16 − 11 = 5
4. Write the answer.
   5 more apples

Check. Match one to one: the 5 extra apples have no partner. ✓

Watch out. Subtract the smaller number from the bigger number. Do not add the two numbers together.

Key words. The box (?) shows the missing number.

Method. To find the missing number, take the number you know away from the total.

1. Look at the total. The total is the answer to the sum.
   Total: 17
2. Take the number you know away from the total. Taking away undoes adding.
   17 − 9 = 8
3. Write the missing number.
   8

Check. Check: 9 + 8 = 17. ✓

Watch out. Do not add the two numbers together. Take the number you know away from the total.

Key words. To take away is to remove some. To count back is to go down one at a time.

Method. Take away 4 from 13 by counting back 4 steps.

1. Start at 13. Start with the whole amount.
   Start: 13
2. Count back 4. Each step back is one less.
   12, 11, 10, 9
3. Write the answer. The last number you say is what is left.
   9

Check. Check: 9 + 4 = 13. ✓

Watch out. Count back, not on. Do not say the starting number as one of the steps.

Key words. To make 10 is to fill up to 10 first, then add the rest.

Method. Fill the first ten frame to make 10. Then add what is left over.

1. Put 6 counters on the first ten frame. We need 10 counters to make a full frame.
   6 counters
2. Add 4 more to make 10. 6 needs 4 more to make 10.
   6 + 4 = 10
3. Use the rest of the 9. 9 − 4 = 5, so 5 counters are left over.
   10 + 5 = 15
4. Write the answer.
   15

Check. Check: start at 9 and count on 6. You also reach 15. ✓

Watch out. Fill the frame up to 10 first. Do not forget to take the counters you used from the second number.

Key words. A double is two equal amounts, or a number added to itself.

Method. A double is a number added to itself. Double 8 is 8 + 8.

1. Make two rows of 8. Both rows are the same, so the two numbers are equal.
   8 and 8
2. Count all the things. Count one row, then count the other row.
   8 + 8 = 16
3. Write the answer.
   16

Check. Take one row away: 16 − 8 = 8. One row is left. ✓

Watch out. A double has two equal rows. Do not forget to count the second row.

Key words. A number bond is two numbers that make a total. The whole is the total. The parts make the whole.

Method. Start from the whole. Take away the part you know to find the missing part.

1. Find the whole and the part you know. The whole is the big number at the top of the picture.
   Whole: 20. Part I know: 13.
2. Take the part you know away from the whole. Subtracting finds the missing part.
   20 − 13 = 7
3. Write the missing part.
   7

Check. Check: 13 + 7 = 20. ✓

Watch out. Start from the whole, not from the small number. Do not add the two parts together.

Key words. To take away is to remove some. To count back is to go down one at a time.

Method. Take away 4 from 13 by counting back 4 steps.

1. Start at 13. Start with the whole amount.
   Start: 13
2. Count back 4. Each step back is one less.
   12, 11, 10, 9
3. Write the answer. The last number you say is what is left.
   9

Check. Check: 9 + 4 = 13. ✓

Watch out. Count back, not on. Do not say the starting number as one of the steps.

Key words. Zero means none at all. We write it as 0.

Method. Zero means none. Adding zero, or taking away zero, changes nothing.

1. Look at the sum: 11 + 0. Find the zero in the sum.
   11 + 0
2. Nothing is added or taken away. The number stays the same as it was.
   11 stays 11
3. Write the answer.
   11

Check. Count 11 things and take away none. You still have 11. ✓

Watch out. Zero does not change a number. Do not write 0 as the answer.

Key words. A fact family is four facts that use the same three numbers.

Method. Two parts make one whole. Each part can be found by taking the other part away from the whole.

1. Put the two parts together, both ways. Adding the parts in either order gives the same whole.
   8 + 6 = 14 and 6 + 8 = 14
2. Take each part away from the whole. Each take-away fact finds the part that is left.
   14 − 8 = 6 and 14 − 6 = 8
3. Write all four facts.
   8 + 6 = 14, 6 + 8 = 14, 14 − 8 = 6, 14 − 6 = 8

Check. Check one fact: 8 + 6 = 14, so 14 − 6 = 8. ✓

Watch out. Keep the whole at the start of a take-away. Write 14 − 8, not 8 − 14.

Key words. A near double is one more or one less than a double.

Method. A near double is one more or one less than a double. Double 6 first, then add one more.

1. Find the double of 6. Double 6 is 6 + 6, two equal groups.
   6 + 6 = 12
2. Add the extra one to 12. 7 is one more than 6, so we add one more.
   12 + 1 = 13
3. Write the answer.
   13

Check. Check: start at 7 and count on 6. You also reach 13. ✓

Watch out. Do not forget the extra one. The answer is one more than the double.

Key words. To make 10 is to fill up to 10 first, then add the rest.

Method. Fill the first ten frame to make 10. Then add what is left over.

1. Put 9 counters on the first ten frame. We need 10 counters to make a full frame.
   9 counters
2. Add 1 more to make 10. 9 needs 1 more to make 10.
   9 + 1 = 10
3. Use the rest of the 7. 7 − 1 = 6, so 6 counters are left over.
   10 + 6 = 16
4. Write the answer.
   16

Check. Check: start at 7 and count on 9. You also reach 16. ✓

Watch out. Fill the frame up to 10 first. Do not forget to take the counters you used from the second number.

Key words. The difference is how many more one number is than the other.

Method. The difference is how many more. Take the smaller number from the bigger number.

1. Count the first group: 18 stickers. Touch each one once.
   18 stickers
2. Count the second group: 12 stickers. Touch each one once.
   12 stickers
3. Take the smaller number from the bigger number. Subtraction finds how many more.
   18 − 12 = 6
4. Write the answer.
   6 more stickers

Check. Match one to one: the 6 extra stickers have no partner. ✓

Watch out. Subtract the smaller number from the bigger number. Do not add the two numbers together.

Key words. The box (?) shows the missing number.

Method. To find the missing number, take the number you know away from the total.

1. Look at the total. The total is the answer to the sum.
   Total: 15
2. Take the number you know away from the total. Taking away undoes adding.
   15 − 8 = 7
3. Write the missing number.
   7

Check. Check: 8 + 7 = 15. ✓

Watch out. Do not add the two numbers together. Take the number you know away from the total.