Here someone made a calculation mistake.
Work out each task yourself.
Compare your result with the one written down.
If it does not match, you have found the mistake.
The example next to it shows the correct answer.
Example
2+1=4→3
5−2=4→3
What does this exercise practice?
Checking other people's results trains self-control and deepens the understanding of plus and minus.
Common pitfalls
Children often believe a written number must be right. Important: always work it out yourself and do not just copy.
How to practice at home
Work out a small task wrong on purpose and let the child find the mistake.
Related: Calculation, Compare