Trouble

My youngest child is driving me crazy. He can't stay still in class. I talk to him everyday before he goes to school, just to make sure he remembers the school rules. Somehow every couple of weeks he seems it get in trouble. Punishments, talks and yelling don't work. What is a mother to do? How can you control some-one else? He just can't sit still for a moment, not at school, home, or anywhere.