On Friday, I finally walked out of an edu-movie without having to scrape off the sanctimony and treacle. Whether heartrending dramas or documentaries, edu-cinema has long gone for the mawkish affectations of ridiculously heroic educators reaching ridiculously noble kids.

After decades of watching (and digging) these movies, it was sheer joy to watch the just-released Bad Teacher, starring Cameron Diaz, Jason Segel, Justin Timberlake, and Molly Shannon. Bad Teacher is rude, profane, frequently mean-spirited, and shockingly cavalier about things we're supposed to speak of in hushed tones. I took my AEI team to see it on Friday, opening day, and not everyone had much use for its gratuitous sex, drugs, and general nastiness--and its failure to push harder on the satirical possibilities.

The complaints are all valid. But, I dug Bad Teacher because it treated teachers, students, and schooling with snark, humor, and attitude, rather than the kid-gloves sentimentality that turns almost every edu-movie into a tedious, predictable morality play.

Now, I love uplifting school movies as much (hell, probably more) than anyone. I get teary-eyed every time I watch Teachers; Stand and Deliver; Blackboard Jungle; To Sir, With Love; Lean on Me; Coach Carter; and the rest of the oeuvre. But running through them is a messianic, sanctimonious vision, in which teachers lose faith, are saved by rediscovering the import of serving their flock, and become agents of salvation. None of this shows much interest in whether unredeemed sinners can be good teachers, whether annoying kids may sometimes have only themselves to blame, or in having fun with the pained routines of the schoolhouse.

And that's a shame, because cinema can help us contemplate and discuss these kinds of questions. I'll lay odds that Office Space has spurred more self-recognition among bosses and office workers than any of yourBoiler Rooms or Wall Streets. That's because earnest sincerity is good at telling viewers what they're supposed to admire, but isn't real good at prompting uncomfortable or complex conversations.

Bad Teacher is full of moments like that. Cameron Diaz, as the dope-addled, hard-drinking, ill-mannered bad teacher of the title, has exchanges with kids like you never see on the big screen. She's unapologetically bored by a moony-eyed kid's awful middle school poetry and tells him that he's never going to do well with the ladies wearing the same battered sweatshirt three days a week. Faced with the perky suck-up who tells her she wants to be president, Diaz asks whether she really means it--and tells her that remark is the kind of obnoxious statement that'll get her punched.

The scenes with the principal, in the faculty lounge, and among teachers staffing lunch, are cringe-worthy rather than saccharine. And, even if that's just a window into my own blackened heart, I found the experience a sweet breath of fresh air.