Cute game you did the programming and he did the art. A nice way of getting him involved in the process and being motivated to learn new things.
Couple nags is that the balloons popping every time you change a menu is irritating since it's slow and does not feel responsive. Also the balloons seems to generate a bit close together and would probably make it more difficult then necessary for a kid trying to learn math.
Wow, it is really amazing and it's a nice and fun way to let your son experience the beauty of programming. I really, really like it. The game feels a little bit slow at times but other than that it is awesome!
Yeah the random spawn location will sometimes put balloons in odd places. To make up for it, I ended up just increasing the rate of spawning the correct answer and added a blue colored balloon which turns all the balloons on screen to the correct answer.