"Good Hair," the documentary by Chris Rock is one of those documentaries where you actually learn a whole lot. Chris Rock explores the world of black hair, triggered by a question from his daughter–"why don't I have good hair?" There's a lot of really interesting stuff in the movie, and Chris Rock is a pretty good interviewer with some very funny lines. I learned a lot and had a lot of fun too. Good criteria for documentary. Here's the trailer. [youtube http://www.youtube.com/watch?v=A68UVn0nMvo?wmode=transparent] Plays through tomorrow at the Grand.