HI Stacy,
It sounds like your son is only behaving in this manner at school. The school needs to deal with this... you cannot. You are not at school with him... it is the teacher's job to make him behave there. I suggest you make an appointment with the teacher and ask what strategies the school is using to help your son. Ask for a review meeting. Be helpful..... explain there is none of this behaviour at home, and noe at nursery. Say your 'confused and concerned' as to why he is behaving this way at school. Ask the school how you can support the school in this matter. HOWEVER, you cannot solve this matter for the school.... the school has to d this.