I wrote this iPad app to show off App Development at the career day at my wife's school (Manzanita Community School, Oakland). It's a simple Angry Birds style "knock down the bricks" game. It uses OpenGL and the Chipmunk physics engine.
I wrote the game so that I could edit the levels in OmniGraffle (see Levels/Blank.graffle). As I demoed the app to each class I got the kids to tweak the level and the name of the app, this way the kids believed they were making their own game).
It was a great success.
Some of the thank you notes I received from the classes are here:
http://cl.ly/1b2l3z3E1A191G2S2F17
http://cl.ly/251S2v1l2P342K3z2r2k
http://cl.ly/1R3a3M3d1T1514010u3J
http://cl.ly/3Z342V3E2S1y2r0v383n
Don't forget to do a git submodule update --init --recursive (to grab TouchOpenGL).
This is not great quality code - it was written in a short weekend as a demo for 4th graders.