School of Rock is a 2003 comedy film starring Jack Black as Dewey Finn, a down-and-out guitarist who finds employment in a prestigious school by disguising himself as a substitute teacher. Questionable, jail-worthy actions aside, the film has many impromptu music scenes, and naturally, they're hilarious Jack Black provides the entertainment through his bumbling, easily excitable portrayal of Mr Schneebly, and its his madcap performance which makes sure this film remains fondly remembered. Perhaps the funniest impromptu music scene of the film sees Dewey forced to explain himself to the Principal (Joan Cusack), as she spots a guitar and overhears loud rock music coming from the classroom. Put on the spot, Dewey uses the guitar to briefly teach a Math lesson, singing questions to the class whilst strumming his guitar.