Agree with others that kids should play with kids clubs. Shaft flexes, length, etc. all designed for the golfer of that age is best. Success is important with all sports. Adults can have trouble playing adult clubs, much less kids. My wife was using a boxed set of Target Adams clubs to start vs using an extra set of mine. Recently we purchased her the Ping GLe2 and we can both see the difference. Start the kid on properly sized clubs and when they can play well enough to get around an Executive Course, look at a better set.
Craig's List and others have lots of kids sets.