Year 1: Fact families: related facts

Key words. Swapping means changing the order of the numbers.

Method. Swap the two parts round. The total stays the same.

1. Write the first sentence. Start with the sentence we know.
   4 + 2 = 6
2. Swap the two parts. Adding can be done in either order.
   2 + 4
3. Check the total. Swapping the parts does not change the total.
   2 + 4 = 6
4. Write the answer.
   2 + 4 = 6

Check. Count on from 4 by 2 to check: 6. ✓

Watch out. Swap the numbers, but keep the total the same.

Key words. A fact family is a set of sentences that use the same three numbers.

Method. Use the same three numbers. Swap the parts for the second addition. Take each part away from the whole for the subtractions.

1. Find the whole and the two parts. The whole is the biggest number.
   Whole 8, parts 3 and 5
2. Write the two addition sentences. Swap the parts round for the second one.
   3 + 5 = 8 and 5 + 3 = 8
3. Write the two subtraction sentences. Take each part away from the whole.
   8 − 3 = 5 and 8 − 5 = 3
4. Write the whole family.
   3 + 5 = 8, 5 + 3 = 8, 8 − 3 = 5, 8 − 5 = 3

Check. Check: 3 + 5 = 8 and 8 − 5 = 3. ✓

Watch out. In a subtraction sentence the whole always comes first.

Key words. The + sign means add. The = sign means the answer is.

Method. Count each group. Then join them with a + sign and write the total after an = sign.

1. Count the first group. Say how many there are.
   4
2. Count the second group. Say how many there are in the other group.
   5
3. Join the groups with the + sign. The + sign shows that we put them together.
   4 + 5
4. Write the whole sentence. The = sign comes before the total.
   4 + 5 = 9

Check. Count all the things in both groups: 9. ✓

Watch out. Put the + sign between the two groups, and the = sign before the total.

Key words. The − sign means take away. The answer is after the = sign.

Method. Start with the whole. Take away the part that goes. Write the sentence.

1. Start with the whole. Count everything at the start.
   Start: 10
2. Take away the part that goes. The − sign means take away.
   10 − 4
3. Count what is left and write the sentence. The answer goes after the = sign.
   10 − 4 = 6
4. Write the answer.
   10 − 4 = 6

Check. Add back to check: 6 + 4 = 10. ✓

Watch out. The sign is a minus, not a plus. Taking away makes the number smaller.

Key words. The whole is the total. The parts are the two numbers that make it.

Method. Take each part away from the whole. Each part gives one subtraction sentence.

1. Find the whole. The whole is the biggest number.
   Whole: 5
2. Take away 2. Taking away the first part leaves the second part.
   5 − 2 = 3
3. Take away 3. Taking away the second part leaves the first part.
   5 − 3 = 2
4. Write both sentences.
   5 − 2 = 3 and 5 − 3 = 2

Check. Check: 3 + 2 = 5. ✓

Watch out. Keep the whole at the front of each subtraction sentence.

Key words. A fact family is a set of sentences that use the same three numbers.

Method. Use the same three numbers. Swap the parts for the second addition. Take each part away from the whole for the subtractions.

1. Find the whole and the two parts. The whole is the biggest number.
   Whole 6, parts 2 and 4
2. Write the two addition sentences. Swap the parts round for the second one.
   2 + 4 = 6 and 4 + 2 = 6
3. Write the two subtraction sentences. Take each part away from the whole.
   6 − 2 = 4 and 6 − 4 = 2
4. Write the whole family.
   2 + 4 = 6, 4 + 2 = 6, 6 − 2 = 4, 6 − 4 = 2

Check. Check: 2 + 4 = 6 and 6 − 4 = 2. ✓

Watch out. In a subtraction sentence the whole always comes first.

Key words. The = sign means the two sides are the same amount.

Method. Work out 3 + 4, then check it against the number that was said.

1. Work out 3 + 4. Start at the bigger number and count on.
   Start at 4, count on 3: 7
2. Compare with what was said. Is the total the same as the number in the sentence?
   7 and 8
3. Write the answer.
   No. 3 + 4 = 7.

Check. Count all the things: 3 + 4 = 7. ✓

Watch out. Work out the total first. Do not guess from the numbers you can see.

Key words. A fact family is a set of sentences that use the same three numbers.

Method. Use the same three numbers. Swap the parts for the second addition. Take each part away from the whole for the subtractions.

1. Find the whole and the two parts. The whole is the biggest number.
   Whole 7, parts 1 and 6
2. Write the two addition sentences. Swap the parts round for the second one.
   1 + 6 = 7 and 6 + 1 = 7
3. Write the two subtraction sentences. Take each part away from the whole.
   7 − 1 = 6 and 7 − 6 = 1
4. Write the whole family.
   1 + 6 = 7, 6 + 1 = 7, 7 − 1 = 6, 7 − 6 = 1

Check. Check: 1 + 6 = 7 and 7 − 6 = 1. ✓

Watch out. In a subtraction sentence the whole always comes first.

Method. Check which sentences use only the numbers 3, 4 and 7.

1. Look at 3 + 4 = 7 and 4 + 3 = 7. Both use only 3, 4 and 7.
   3, 4 and 7
2. Look at 7 − 3 = 4. It uses 7, 3 and 4.
   7, 3 and 4
3. Look at 7 + 4 = 11. It has 11 in it, not 3, 4 or 7.
   7 + 4 = 11
4. Write the odd one out.
   7 + 4 = 11

Check. The family only uses 3, 4 and 7. ✓

Watch out. Look for the sentence with a number that is not in the family.

Key words. A fact family is a set of sentences that use the same three numbers.

Method. Use the same three numbers. Swap the parts for the second addition. Take each part away from the whole for the subtractions.

1. Find the whole and the two parts. The whole is the biggest number.
   Whole 7, parts 2 and 5
2. Write the two addition sentences. Swap the parts round for the second one.
   2 + 5 = 7 and 5 + 2 = 7
3. Write the two subtraction sentences. Take each part away from the whole.
   7 − 2 = 5 and 7 − 5 = 2
4. Write the whole family.
   2 + 5 = 7, 5 + 2 = 7, 7 − 2 = 5, 7 − 5 = 2

Check. Check: 2 + 5 = 7 and 7 − 5 = 2. ✓

Watch out. In a subtraction sentence the whole always comes first.