Get him a copy of a tabletop role-playing game, a notebook for writing down campaign ideas, a couple of people willing to include him in their group as a part-time DM, and (importantly) an understanding from the teacher that when he is sufficiently done with the classwork, his time is his so long as he isn't disrupting other students.
Although my 8-year-old son likes his teacher, he is frequently bored at school. He attends a high quality suburban public school in the United States. He has a lot of traits in common with LessWrong readers, and we would like advice for what he can do to counter his boredom. Many of you must have found grade school more or less tedious. What were your coping strategies?