Add "urban school drama" to the quickly growing list of movie genres that should be temporarily retired, if not permanently put to sleep.

The genre actually began and peaked with 1955's "The Blackboard Jungle," but is currently enjoying a renaissance, due to films like "Stand and Deliver" and "Dangerous Minds." But less-original creations like the thriller "The Substitute" and the unfunny parody "High School High" offer proof that it may be tapped out permanently.

And despite adding its own variety of story twists and turns, "187" is just more of the same. In fact, since it wastes a great lead performance from Samuel L. Jackson, the film might even be a bigger disappointment than the others.

One thing is certain, however. While the film pretends to be a cautionary tale about violence in our schools, the unpleasant direction it heads toward will probably be misinterpreted by a lot of audiences, and "187" (police and gang slang for murder) will be seen a sending the wrong kind of message about the problem.

Jackson stars as Trevor Garfield, a dedicated Brooklyn science teacher who barely survived an attack from an irate student he was flunking. Scarred physically and emotionally, he turns up a year later as a substitute teacher in an L.A. high school.

Though he impresses his new co-workers — including Dave Childress (John Heard), a victim of teacher burnout, and Ellen Henry (Kelly Rowan), a naive young computer-science intructor — and reaches out to some of his pupils, Trevor finds that things are pretty much the same elsewhere.

Constantly challenged by the gang members in his class, especially the abusive, drug-addled Cesar (Clifton Gonzalez Gonzalez), Trevor slowly descends into madness — first confronting the students at their homes and then turning to desperate, violent revenge.

To his credit, Jackson almost saves the movie single-handedly, and for that — if not the remainder of his work — he deserves more than just one chance in a starring role. Unfortunately, he's undermined by the inconsistent, at-times preposterous, script from Scott Yagemann, a former L.A.-area substitute teacher.

Almost as unconvincing as Trevor's turn to the dark side is his contrived romance with Ellen, which feels more like a plot device than natural character development.

Of course, it doesn't help that Kevin Reynolds ("Waterworld") has given things a jarring, music-video look (including camera "shivers" and "slo-mos") that detracts from the action, especially when the film changes gears from drama to thriller.

Frankly, the film would have been better off if it had remained a straight drama, especially given its powerful performances (Rowan, Gonzalez and Heard all lend able support).

"187" is rated R for almost non-stop profane language, violence, drug use, racial epithets, a few shots of violent gore, brief nudity and some vulgar references.