A voice of reason. If this is the first "performance" ball, I'd also suggest either a low level entry piece like a Sligshuo, Tornado or a Trop. Storm, or a used and plugged mid-level piece with a simple, symmetrical core. With some training and still growing, 11 or 12 lbs. will quickly become too light, and if this is to test whether bowling is a long-term occupation, I'd rather wait for the next ball with a more potent and probably heavier piece.
Getting the basics right is much more important than a high end recative, esp. in the hands of a beginner. Only thing to watch out for is to coach the kid and have a keen eye on the player potential - many kids I know from my club's youth program also start with entry level balls, but quickly "grow out of them" - they start ripping the cover off of the ball and develop doubtful release habits, overpowering the ball. My advice: start small, but be prepared to take the next equipment step quickly!
