rgosit is right
Being that young I would recommend light workouts until he develops a base. Remember, he is still growing and any muscle tears, strains, or pulls could prove serious. Start with at least 10 minute warmup. Hit Flat Bench, Squats - Full range, and Deadlifts. I would get him familiar with these exercises for the next 2-3 years before introducing anything else. Go light for the first 3 months, 15-20 reps for deads and squats, 12-18 for bench.