Make an animation with two stick figures moving at the same time: 1. One starts at the top left corner of the frame and moves right. 2. The other starts in the bottom right corner of the frame and moves left.
It is OK if the animation does not work once the figures get to the edge(s).
Remember: start with one moving figure, work through the process step by step until you have one figure moving correctly. Then add the other figure.
Exercise 6.5.5 from the book.