My son is able to do the mental addition well and I thought everything was good until we got to this lesson. The worksheet asks for a first and second number when adding two digits. The book numbers add the tens first then the ones, so for 37 + 46 = 70, 83. My son is doing it backwards, he is adding the ones first then the tens so his answer would be 43, 83...Is this ok? Why or why not?

Thanks for the help,
Michele

Dear Michele,
Is he doing his adding in his head, without paper, pencil or the abacus? If so, then he is doing what he needs to do. However, it is wise to try to teach him multiple strategies for solving the same problem. The more ways he can solve it, the more adept he is at mathematical thinking.
Nancy

Dear Nancy,
Yes, he does them in his head without paper, pencil or abacus. He just does them his own way, not the strategy I am teaching.
Thanks,
Michele