I do not like to complain about teachers. They have one of the hardest, least appreciated jobs there is to have.
No doubt about that. But, with their job also comes "responsibility" - to uplift a student intellectually and not to beat them down when they tend to do well.
Your son is accelerated so much because he is good at math, obviously. So, there is no reason to hold him back. If I were you, I would let him work on his weak areas in the summer (practicing error checking, slowing down and reviewing work). Go for it!
