"I'm Mrs. Stephenson," says the high school teacher to her new students, glowering like a drill sergeant. "This is your culinary arts class."

The teacher adds an admonishment that could have been lifted from any boot-camp picture. "Some of you will remain here, some of you will not remain here. . . . Whatever you heard, it's 50 times worse."

Welcome to Room 325 at Philadelphia's Frankford High, where metal detectors and police are part of the landscape. It is here that Wilma Stephenson, the explosive African American subject of Jennifer Grausman and Mark Becker's engaging documentary "Pressure Cooker," grooms inner-city seniors for a shot at culinary-school scholarships.

A veteran of almost four decades at Frankford, Stephenson emerged from childhood poverty and years as a domestic cook. As a movie character, she comes out of the same tradition as the music teacher impersonated by Meryl Streep in "Music of the Heart": the taskmaster who inspires embattled kids to lofty heights.

That said, Streep's Roberta Guaspari could never get away with the sorts of racially loaded remarks deployed by Stephenson, who uses her blackness and humble origins as a wedge with which to pry her students out of their fast-food mind-set.

Stephenson is appalled when the kids react blankly to her flip reference to Habitat for Humanity, snapping, "God! Some of you are probably living in their houses!"

This sarcasm makes Stephenson such a celluloid natural, lending a needed edge to an otherwise conventionally rendered documentary. Grausman and Becker trail three promising acolytes as they slice and dice their way from a preliminary cooking competition to scholarship finals. A broken-home survivor, a bruising football star and an African emigre convey camera-friendly personalities.

If the filmmakers do little to expand the vocabulary of the genre, they enhance our appreciation of that most undervalued sector of the American workforce, the city schoolteacher. "Pressure Cooker" may not get the royal, Conde Nast-magazine hype accorded that upcoming Julia Child movie (starring, who else, Meryl Streep), but it merits a place of honor at the table.

-- Jan Stuart (July 17, 2009)

Contains mild adult humor.