Perhaps there needs to be some education of the other students and some anti-bully activities. If your son is going through this then so are other kids. The school needs to get a handle on it now before it becomes widespread. Your son deserves his education and a safe environment. Tell them you want an aide to supervise him in these classes so that he is not picked on. Let them know it is there job to know what is going on, even in whispers. i am a teacher and you have to stay on these issues constantly or it escalates