Try to catch him being good and identify the circumstances surrounding the times when he is behaving. Sometimes we get so caught up when kids misbehave that we forget about the circumstances surrounding them behaving. See if you can identify some things that help him behave and then integrate those in to more parts of his life. Also consult with his teacher about this can compare notes. Kids act differently in different environments so good communication between you can the teacher will be important.
Also seeking out a child psychologist and getting your child assessed is never a bad idea. You may discover some things that may be contributing to his bad behavior and child psychologists are experts at helping solve these sort of problems. Maybe he has a learning disability or ADHD or maybe he is simply stressed about something else at school. A child psychologist can help you explore all of these areas. Talk to the school counselor and see if they have any referral information.
Also continue to try and keep a dialogue open with your child regarding these situations. Since they are living it, they know best what is going on. Please continue to ask questions and see if you can get some answers. Try to approach him calmly and openly and it is more likely that you will get less defensive responses.
We wish you well and hope that you can take care! If you need to talk further, please call our hotline. We are here to help!
Boys Town National Hotline-A Resource for Parents and Teens