I stumbled across this randomly on YouTube today and had to share. The first 3/4 of the video are a chemistry experiment breakdown of what goes into a glow stick and what each of those ingredients is meant to do. But what makes me LOVE it is that, at the end, all of this coalesces into a fine explanation of the difference between light-absorbing dyes and fluorescent dyes. Come for the glow-stick "how to", stay for the better understanding of how light works and how it influences what you see!
Maggie Koerth-Baker is the science editor at BoingBoing.net. She writes a monthly column for The New York Times Magazine and is the author of Before the Lights Go Out, a book about electricity, infrastructure, and the future of energy. You can find Maggie on Twitter and Facebook.