A precious scrap of American history, this documentary by Mark Landsman tells the story of Conrad Johnson, an inspiring music teacher at Houston's predominantly black Kashmere High School who turned the school's jazz band into a fearsomely hard-charging funk outfit in the 1970s. Most high school stage bands at the time were white ensembles playing ancient big-band numbers, which made Johnson's innovative combination of original funk tunes and big, muscular horn sections seem even more dramatic. Rehearsals for a 2008 reunion concert, honoring Johnson on his 92nd birthday, give his former students a chance to recall his impact on them as a mentor (particularly the boys, lower-class kids who were galvanized by his passion, discipline, and professionalism). Some of the interviewees tend to oversell the story emotionally, but the band's electrifying music speaks for itself.