This assignment was to teach the principles of Squash and Stretch, Weight and Timing. As well as reinforce the idea of Slo-in and Slo-out.
Imagine a ball bouncing up and down, forever and ever. Never losing any energy in its bounce. Thats the idea behind this assignment.
The main idea to put across is that this ball is real, it has weight and it is affected by gravity. Gravity slows the upward motion of the ball as it travels upward, then it pulls the ball down at ever increasing speeds before the ball bounces back up and the process repeats itself. At the beginning of the bounce, the ball is moving the quickest, and therefore there is a large space between the position of the ball at one frame to the other. To give the illusion of it slowing down, the distance the ball travels compared to the frame before gets less and less. Then at some point the ball begins its journey back down. Now it is picking up speed, so each distance it travels becomes greater and greater, frame by frame.
If you pause the video, you should be able to go through it frame by frame using the arrow keys. This will allow you to see each drawing clearly, and you can better judge the spatial relationships from frame to frame. Also if you do this, notice the three frames at the point of contact with the ground. In the frames before and after contact, the ball is stretching vertically. At the point of contact, the ball is squashed. The idea here is to emphasive the action of the ball. At the frames before and after, the ball is moving quickly and we can exaggerate that motion by stretching the ball along its path of motion. The squash then really makes you feel that moment of impact where the ball is changing directions. This concept is vitally important in animation and is used all over the place in cartoons.