At first the Jackie Robinson Steppers—a real marching band that’s part of a Brooklyn after-school program for 8- to 18-year-olds—seem to be the subject of a documentary. But soon it’s clear that three of the teenage girls in the group are the main characters in a fictional story. The best friends have a lot to deal with—their parents range from borderline neglectful to supportive if complicated, and the closing of the local asbestos-ridden high school may split the girls up (though it won’t cure the two who have asthma). One girl’s melancholy (beautifully expressed by actress Kerry Washington) is a response to a fractured romance, and the specters of pregnancy and even suicide loom, though writer-director Jim McKay bravely refuses to oversimplify the reasons behind teen motherhood. He also uses documentary elements and style deftly, if largely to validate the realism—a white guy, McKay’s had to field questions ever since his 1996 Girls Town about why he makes movies about young and minority women (2001). With Melissa Martinez and Anna Simpson. 96 min.