Im a 6th grader my father had about the same issue with me when i was younger what he did was talk to the teachers about it nothing really changed but i ended up going to another school enyways.I changed my attitude about things because i was being acused of having ADD  and i also had the motovation of going to a new school witch gave me a freash start.So to answer you're question i would just ask you're son what HE WANTS TO DO and compromize with him.

If you have reported the matter to the class teacher and it continues to persist, then the next steps are to confront the Principal about the matter. Let them know that this is a form of bullying and it is not tolerated at any level/age. Let them know if the bullying does not stop that you will report them to the Board of Education. I recently had the same situation with my son where another child was bullying him, but the teacher and principal were not aware. Once I brought it to their attention, they were very quick with resolving the situation. No problems since. Good luck!

Talk to the teacher and do it now.  That classroom is out of control!! The teacher is responsible for his safety at school and if he or she is that insensitive, think of what that teacher is teaching the kids!!!
If you get nowhere with the teacher...got to the principal...and then the school board.  Kids need to learn caring and compassion.  
Move forward on this on this or his grades will get worse.