Academy Award-winning documentarian Davis Guggenheim’s (“An Inconvenient Truth”) most recent film intends to do for public schools what his last one did for the environment — convince the nation that all’s gone to hell and we’d better act now.

But in “Waiting for Superman,” screened Wednesday night at Silver Spring’s SilverDocs movie festival, Guggenheim opts for practitioners over politicians to sell his cause. Instead of Al Gore with Powerpoint, we get schools Chancellor Michelle Rhee with actual power to close schools, fire teachers, and well, we know the routine.