My eldest worked out by increasing the size of an animation over many frames makes it look like it grows. This is important, especially for kids in the early primary years. After a few days they had realized they could create their own stick figures to animate and had begun to use the simple drawing tool to save their own stick figure props like beds, cannons and barbells.
Despite my own beliefs in the capacity of children and their ability to do things that we never acknowledge (so never see them do), I was amazed at the speed at which they picked up the basic concepts using Pivot.