When you put together two parts, you make a whole. You can also break a whole apart into two parts.
Key idea
A number can be broken into two parts in more than one way. 5 is 4 and 1, or 3 and 2, or 2 and 3, or 1 and 4, or 5 and 0.
Why it works
Moving one bead from one part to the other does not change the whole. So many different pairs make the same number.
Worked example: All the ways to make 4
Find all the ways to break 4 into two parts.
- 4 and 0
- 3 and 1
- 2 and 2
- 1 and 3
- 0 and 4
Answer: 5 ways
Common mistake
Finding one way and stopping, as if it were the only answer. There are many! Move one counter from one part to the other and say the new pair.
For grown-ups: Hide some of 5 pennies under a cup. Your child says how many are hiding. Then try all the other ways.