Maybe you should try setting up a reward system for the child to behave well and complete his work. Find out what motivates him and use that to reward him when he does well. You may also want to have someone else, another teacher, an administrator, a counselor, etc., come into your room an observe the student. This way, that person can also tell the parent what you are seeing is also what they are seeing. They may also be able to offer insight into how to help the student be successful as well.

I am only speaking to this as a parent. My daughter's teacher has told me that she is one of the highest children in her class and needs to be challenged and wants to keep pushing her with her writing. I appreciate that. But when my daughter gets home she is completely exhausted and is not a child that will lay down and rest. She is just wild! I was convinced that she behaved the same way in school. I recently spent three weeks in her class completing a clinical experience and watched my child behave perfectly. I went to the teacher and asked her if that is the way she always acts and she said yes. I knew my daughter was mentally exhausted at home. I have asked her teacher to send home books that were not as challenging for her to practice because she had expelled so much energy at school. It might be worth giving it a try to see how things go for a day. I wouldn't change things for more than a day though. I would think you would see a difference pretty quickly.

I would suggest talking with the student to see exactly why he/she is behaving inappropriately (whats going on and is the work to difficult or too much) and what might help to alter this behavior. I would do the same with the parent and discuss this with both parent and child.

How are his grades? Is it possible perhaps he's the opposite: not challenged enough? Rather than "easier" assignments I would focus on redesigning them - make them more interesting for him. Perhaps he is unable to focus because he get frustrated with the way it is presented.

I would make sure I let the mom know that her child is exceling in class and then once I found a solution such as a reward system I would make sure the mom knew what plan was implemented so she could continue the same system at home.

I would let the parent know that by giving the student anything less that what you are currently providing would be a disservice to the student based on his data.