Here is my completed experimentation without a stretch effect:
Conann told use today that we should aim to change alter the actual geometry of a model as little as possible. Instead you use locators to create a rig. For the stretch and squash effect you have three locators. A trans locator which direct where the ball is in a key frame and where its going, a scale locator which is what you use to create the squash and stretch and finally a rotate locator which you make the ball spin with. Parent these together with your shape and you can make any shape bounce across the screen. And as such our homework for net week is to animate three different types of balls bouncing across a screen using locators: a bouncy ball, a bowling ball and a super ball.