I've been working with Cub Scouts all week as rangemaster for BB guns. BB guns are a huge hit with Scouts, and whenever my wife is the director she makes sure range time is a HUGE part of the schedule.
Be guns, archery, and sling shot all morning until lunch, all week.
Let me tell you, it's an exhausting job trying to maintain safety and control, not to mention actually TRAIN the little buggers productively. But they learn.
Their mandatory training is done (Monday, Tuesday, Wednesday, standing, kneeling/sitting, prone) and Thursday/Friday are strictly "shoot for fun".
All I've got to say is "make sure it's fun for your son". Shooting should always be a fun activity!