Hinge actions
Clear demonstration of the hinge actions. Preferably showing the specifics of each without mentioning anything about any of the others ie. when talking about verticle hinge do not mention horizontal.
Then you could follow that with a short demo of them in action and make comparisons on short shots ie. verticle hinge will cause ball to do this .....
Horizontal will make ball to this ....... whereas vertical made it do this....
Hope you get my idea
Chris