Sometimes the calculation goes past the 10.
Then you split the problem into two steps:
Step 1: First calculate up to 10.
Step 2: Then add the rest.
Example: 8 + 5
8 + 2 = 10 (first up to 10)
10 + 3 = 13 (then add the rest)
Calculate step by step: first up to 10, then add the rest.
Example
What does this exercise practice?
This exercise teaches how to split numbers cleverly to calculate across the 10, one of the most important basic techniques for mental math.
Common pitfalls
Many children try to solve the problem directly, without the in-between step across the 10. That leads to mistakes. It helps to say the split out loud: how much is still missing up to 10?
How to practice at home
While cooking or baking, count together: we have 8 noodles, we need 13, how many are still missing? Use the ten as a stopover.
More for parents: matheeule.de/eltern