I don't know; I didn't attend, and the videos on
Apple's page require the purchase of a Mac or iOS device to view. "System Requirements: To watch the streaming version of this video, use the latest version of Safari on a Mac running OS X Lion or later. Alternatively, you can watch this video in the WWDC app". Without any other information, my guess is that kids are programming applications for OS X, as unlike iOS application development, OS X application development doesn't require an ongoing subscription. Other results that Google dug up deal with parental control for in-app purchases. Could you explain further?