Hail! Hail! Jack Black: He’s the clown king of rock & roll. Black is ideally cast as Dewey Finn, a metal-head who’s just been fired by his no-talent band. Since he needs rent money, Dewey scams a job teaching nerdy fifth-graders at a prep school run by a tight-passed principal (the ever-hilarious Joan Cusack). When the kids get tired of all-day recess, Dewey teaches them rock & roll, Led Zep-style. This is pretty tame stuff for a wild man like Black, not to mention screenwriter Mike White. (Chuck and Buck The Good Girl) and indie director Richard Linklater (Dazed and Confused, Waking Life) — kid-friendly crowd pleasers are hardly their meat. But even education can’t kill the demon of fun in Black. Enroll in his class and you won’t stop laughing.