D.S.
I would meet with the teacher and see how much seat work they are doing. Most five year old children especially boys can not sit for long periods of time. I own a preschool with a kindergarten program and the children change activities every 30 minutes. When they finish their work they are permitted to get a book or puzzle until their friends finish their work. Is he finishing his seat work first, maybe he is not challenged enough. When a child finishes early and the other children are not finished why can't she allow him to get a puzzle or a book to occupy him while the others are finished. Children who are bored can tend to be disruptive, so I would also ask if she could give him additional coloring work, or cutting work, to keep him busy and seated.