David Guggenheim, the man behind An Inconvenient Truth and Obama’s 2008 DNC bio-infomercial, has just released another film — this one a stabbing indictment of teachers’ unions and a plea for more charter schools, titled Waiting for Superman. Democrats for School Choice hosted an advance screening of the documentary, to which black clergy, New York City education chancellor Joel Klein, and National Review were invited. The school-choice cause evidently transcends traditional ideological boundaries.

Waiting for Superman intends to influence policy, yet its narrative follows not politicians, but five children. Bianca, Daisy, Emily, Anthony, and Francisco come from diverse locales — Harlem, L.A., Silicon Valley, D.C., and the Bronx — and are black, Hispanic, and white, but they share the same basic problem: Each is consigned by geography to an inadequate public school. Each wants a choice.

The stories — of Bianca, whose single black mother struggles to afford parochial school but misses the final payment that would let Bianca attend graduation, and of Anthony, who carries a picture of his dead, drug-using father as he seeks a spot at a rare charter boarding school that might keep him away from the streets, to name two — are heartbreaking. But the real message of the movie is revealed in the scenes of the adults who produce this heartbreak. Superman’s most memorable episode is the cartoon illustration of the “lemon dance,” in which school principals waltz their “lemons” (teachers who just can’t teach but can’t be fired) from school to school. The musical number would be hilarious if it weren’t so devastating. So, too, for the shots of the infamous “rubber rooms,” where middle-aged teachers sit in school kids’ chairs, playing cards or laying their heads on their desks to sleep, collecting full pay and pensions.

Guggenheim chooses one champion and one villainess. Michelle Rhee, the chancellor of D.C. schools, is energetic and assertive. She bluntly admits that D.C. students “are getting a crappy education right now,” she fires a couple hundred incompetent educators, institutes some incentive pay, and starts to turn D.C.’s schools around. Randi Weingarten, president of the American Federation of Teachers (AFT), and Rhee’s foil, is on the defensive. She seems most solicitous about the egos of teachers; a speech to her union culminates in the cry, “You are heroes!” In her interviews, Weingarten reminds us what good-hearted people teachers are, and condemns school-choice advocates for demonizing teachers. She has maintained this pattern off-screen as well. “It’s in vogue to bash teachers and unions rather than celebrate the work they do to help kids,” she said, responding to Superman. “That being said, I’m a big girl.”

Weingarten, obviously, can take the criticism, but she hasn’t rebutted it. Perhaps it augurs victory that the only thing she can find to fault is her opponents’ tone of voice. For now, though, Weingarten still has the power and the money. Weingarten’s AFT funneled over $1 million to defeat D.C. mayor Adrian Fenty (who appointed and supported Rhee) in the recent Democratic primary. The winner, Vincent Gray, used his victory speech to announce his desire for “a strong, empowered chancellor who works withparents and teachers.”Translation: Rhee is out. This is part of a pattern. Guggenheim, whose political sympathies are normally liberal, admits that the Democratic party is, on education policy, a “wholly owned subsidiary of the teachers unions.” The AFT and NEA — combined, the biggest campaign contributors in the U.S. — send more than 90 percent of their donations to Democrats.

Last week’s D.C. primary is a fitting political backdrop to the narrative of Waiting for Superman. Unions stood in Rhee’s way every step of her chancellorship. An unforgettable scene in the documentary shows Rhee sitting aside from a podium, shouted down from her speech by members of D.C. teachers unions, full of sound and fury. “We will not be silenced,” a teacher snaps. Don’t doubt her.