Rather than going for Bass it may be far more fun for a youngster of that age to start with Bluegill. These can be caught relatively easily with fun, light weight gear. They can generally be found any where you can find brush or weeds in 3' to 10' of water. You can catch them with 4# line, a small "pencil" type bobber, a split shot, a #10 long shank hook, and a redworm threaded on the hook. With a Snoopy-type rod/reel combo from Walmart and everything else including a 50 count pack of redworms it should set you back less than $35. Good luck, hooking a kid on fishing.

Tight lines,
Wade