Swap the numbers, the result stays the same!
Example: 23 + 45 = 68 and 45 + 23 = 68
The number filled in shows the solution.
Example
23+45=68↔45+23=68
For parents
What does this exercise practice?
This exercise teaches the commutative law of addition: the order of the addends does not matter, and the result stays the same.
Common pitfalls
Children are often amazed that the result really stays the same. Some believe the order must make a difference. Letting them try it themselves convinces them best.
How to practice at home
Two kinds of coins on the table: count one kind first, then the other, then the other way round. See that the total stays the same.
Related: Calculation, Inverse