Martial arts and music study - they both have a way of developing patience, perseverance, listening intently, paying attention and following the instructor closely. I am not sure about other sports, but, these two things improved my son's focus, attention and concentration like no other things that we tried (it almost feels like we tried it all!). There were other big benefits as well, but these are relevant to your question. Maybe group music lessons will help him to work with other kids in his group - the younger set has group music lessons that involve a lot of activity and movement.
