It's not so much a function of knowledge as it is a function of doing it. I know that I'm highly biased, but my kid is flat out cool. She loves figuring things out and has a wonderful mischievous attitude to boot. Simply, when she's awake and I'm not working, I'd rather spend time with her (rather than stay active which would keep me alive longer, thus meaning more time with her).

For me, it was the sound that got me hooked on this particular app. It's the kind of godawful noise that would wake the dead just long enough so they can do their pushups and shut the damned thing up...:)