This one always arrests the physics major types. Maybe this predicts something about K, it was one of her favorites. Either that, or being able to reach the balls had something to do with it.
I liked this quoteThis is B launching a ball down a roller coaster sort of track, it only makes it to the end if there are no balls stuck in the valleys, and you launch it just right. He kept climbing the stairs to launch more balls to try to get it to go all the way, but he always got out of the way of other kids wanting to try it too. His patience paid off finally!