- 8C10. Models of the Universe
- 8C20. Black Holes
- 8C20.30 Saddle Shape A ball is not stable when placed on a stationary saddle shape, but surprisingly does become stable if the saddle shape is rotated.
- 8C20.50 Gravitational Waves Ripple Tank Simulation Fill tank with water, run drill, and observe waves rippling through the water.