One more rap post for the road.
One of the other artists John introduced me to was MC Hawking. Using a text-to-speech program, his raps are basically gangsta physics. Nerdcore, they call it on Wikipedia.
From his greatest hits album, A Brief History of Rhyme, here's "Entropy," which explains the measure of uniformity of the distribution of energy in a way even I can almost understand, sampling Naughty by Nature in the process. It even edits out the bad language, so feel free to show it to the kids.
By the way, for the record, Stephen Hawking is a fan.