I suppose that the app is useful, but the design is really weird. Do you think that any kid is going to play your game? If e doesn't gat a candy, a present or 15 minutes of Jetpack Joyride as a reward.
Sorry if I'm too harsh. It's just that I believe that kids love beatiful apps. And I can handle an ugly app if it's useful (I'm talking general and don't mean that your app is ugly).
Anyway, hope that your app works. I don't have kids so I cannot check out if it does, but I wish you luck.