GoalFind number bonds, including pairs that make 10, and find a missing part.
New words
number bond · two numbers that add to make a totalmissing part · the part we do not know yetdomino · a tile with two groups of spots
Explanation
Two numbers that add up to make a number are a number bond for it. 4 and 2 make 6, so 4 + 2 = 6 is a number bond for 6. A domino shows a number bond: the spots on the two halves are the parts. If we know the whole and one part, we can find the missing part. If the whole is 10 and one part is 3, count on from 3 to 10: 4, 5, 6, 7, 8, 9, 10. That is 7 more, so the missing part is 7. The number bonds for 10 are very useful: 1 + 9, 2 + 8, 3 + 7, 4 + 6 and 5 + 5.
Worked examples
This domino has 3 spots and 2 spots. 3 + 2 = 5 is a number bond for 5.
The whole is 10 and one part is 3. Count on from 3 to 10 to find the missing part: it is 7. 3 + 7 = 10.
Number bonds for 7 are 6 + 1, 5 + 2 and 4 + 3. Swap the numbers and they still make 7.
Class activity
Bean split: take 8 beans and two cups. Put some beans in each cup and write the number bond, for example 5 + 3 = 8. Tip them out and split them a new way. Keep going until you cannot find a new way. Then play ‘make 10’: your partner says a number, you say the number that goes with it to make 10.
Practice
1
How many more counters fill the ten frame to make 10?
3 (7 + 3 = 10)
2
Write a number sentence for this domino.
4 + 3 = 7
3
The whole is 9. One part is 4. What is the other part?
