“Tell how to make 10 when adding 8+5.”
Actually, the kid was right. If you add 8+5, then you can’t make ten.
If they had asked: “If you have 8 units and 5 units, how could you group them into 10 units”, then the 8 and the 2 would be relevant.
They, however, ask the kid “when adding 8+5”. When one adds 8+5, one gets 13.
It’s so convoluted, I don’t understand the point of doing this exercise. Are they not teaching the addition/subtraction tables anymore?