Swap the numbers, the answer stays the same!
Example: 3 + 5 = 8 and 5 + 3 = 8
The filled in number shows the answer.
Example
3+5=8↔5+3=8
What does this exercise practice?
This exercise teaches the commutative law of addition: the order of the addends does not matter, the answer stays the same.
Common pitfalls
Children are often amazed that the answer really stays the same. Some believe the order must make a difference. Letting them try it themselves convinces best.
How to practice at home
Two kinds of fruit on the table: count apples first, then pears, then the other way around. See that the total does not change.