In 1983, the BBC aired a six-part series called Fun to Imagine with a simple premise: put physicist Richard Feynman in front of a camera and have him explain everyday things. In this clip from one of the episodes, Feynman explains in very simple terms what fire is:
So good. Watch the whole thing…it seems like you get the gist about 2 minutes in, but that’s only half the story. See also Feynman explaining rubber bands, how trains go around curves, and how magnets work.