What I did for my daughter at a young age was with one of those $10.00 spinning spinning rigs from Wally World. Finf some of those elongated plastic bobbers, one end is slightly heavier than the other. Tie the light end to the mono line, oon the other end 4x-5x tippet about 2' and a dry fly. The only trick is to get him to stop the line beforit hits the water, it flips the bobber and "presents" the dry fly with a nice turn over. Now he's sight fishing a dry fly. For crappie and blue gill a nice size 12 or 14 elk hair caddis works wonderfully.
Pete