You just do what you have to do. I have no idea what level DS is reading in school. Last year at this time he was at an O, now he is probably at an L. I donated about 50 books to the classroom and DS has been reading an "Earth and Space" book that I sent in, which he really liked, but another boy told him he wanted to read it and DS is so nice, he just gave it to him.
The teacher told Dh that DS has a "book box" with books at his level (whatever she considers his level) but he often chooses lower level books so he can fit in with the other kids. She thinks that's perfectly Ok. To me, that's just more evidence that he should be accelerated.
As for math homework, I finally just sent in a note saying that I hope she understands, but he won't be doing it anymore as it is very far below his academic level, and I will have him do something more appropriate. She previously agreed to give him harder level math, but then just never did it. I know I'm not popular with the teacher anymore, but sometimes you have to put your foot down and just do what you need to do for your child.