“Dangerous Minds,” “Stand and Deliver,” “Lean on Me” — movies about heroic teachers changing students’ lives, and all movies shown in Miss Elizabeth Halsey’s seventh grade English class at John Adams Middle School.

But Miss Halsey (Cameron Diaz) isn’t trying to inspire, motivate or teach. She isn’t trying at all. She’s a “Bad Teacher,” and for all the bad reasons.

“Shorter hours, summers off, no accountability.”

It’s only when her gold-digging doesn’t yield paydirt that she returns to JAMS, as its called, for a second year. From the heel of her stilettos to the top of her bimbo coif, Elizabeth Halsey is a man-trap, on the prowl for a rich husband or at least the cash to buy the breast implants that will land her one.

“Bad Teacher” is a raunchy comedy that promises, from its title to its casting, a “Bad Santa” riff on a sacred institution. Who hasn’t heard that title and that leading lady and thought back to MTV prehistory and Van Halen blitzing through “Hot for Teacher”?

Set Diaz up against the gifted Brit comedienne Lucy Punch (“Dinner for Schmucks”) competing for the attentions of the rich guy dabbling in teaching (Diaz’s ex, Justin Timberlake), with Jason Segel and John Michael Higgins as interested bystanders, and the laughs find themselves, right?

Only they don’t. “Bad Teacher” is a pulled punch, a pot-smoking/kid cussing/teacher copulating farce that is less than the sum of its parts. The writing seems forced, with shocks spaced out every few minutes. Jake Kasdan’s direction is unobtrusive, but the film isn’t shot or edited in ways that help the comedy deliver surprises or develop momentum. The laughs are kept at arm’s length.

The other teachers know Elizabeth isn’t good at her job. They drop hints. She ignores them, lights a pipe in the parking lot, shows up drunk and takes bribes from parents rather than teaching the kids.

If only, if ONLY she had bigger breasts. She might have landed that rich fiance whose mom was wise to her, or had a shot with one of the Chicago Bulls — whom she apparently went through in her pursuit of NBA cash.  Her second year at JAMS, she’s willing to embezzle from the school car wash, cheat to win a bonus, whatever it takes to get those new breasts.

Diaz is dolled up and backlit to beat the band here, and hasn’t looked this glamorous since her “Something About Mary” hair gel days. She is believably callous and cruel, less convincing as Elizabeth starts to grow a heart. Well, except for the scene where she hurls kickballs at students who give her incorrect answers as she drills them (literally) on “To Kill a Mockingbird.”

Timberlake is amusingly ditzy and Punch, slinging a Chicago accent and playing a version of every hysteric who shrieks “I’m ON to you” since Ferris Bueller’s principal, is game. Segel has few funny lines and fewer funny scenes to play.

Despite the timing of this, coming in the middle of what some teachers regard as an assault on the profession coming from all sides, there’s no reason “Bad Teacher” shouldn’t work. But in our post-”Hangover” era, there’s not much shock in a molder of young minds writing “stupid” and “stupider” on seventh grader’s tests. “Bad Teacher” starts the school year with rude and randy promise, but never quite reaches graduation.

MPAA Rating: R, for sexual content, nudity, language and some drug use.

Cast: Cameron Diaz (Elizabeth), Justin Timberlake (Scott), Jason Segel (Russell), Lucy Punch (Amy)

Credits: Directed by Jake Kasdan, written by Gene Stupnitsky and Lee Eisenberg, produced by Jimmy Miller.  A Sony Pictures release. Running time, 1:32.