Alright so I looked over what is in Github, and decided we weren't really very far from Practice Assignment #3, so I torched what was up there and reloaded. Check Email for more verbose description of what's going on.
The rain functionality has been added.

It works well for the cubes, not so well for the teapots, and not at all
for the skulls. The speed and the distance between falling objects can
be changed relatively easily. Let me know if you have any concerns.