For a film that only scratches the surface of its topic, “Bully” carries a devastating emotional punch. A powerful examination of aggressive behavior in American schools, the movie focuses on a handful of families affected by bullying. The film will leave you spent, disturbed and sorrowful. But buckle up. “Bully” is mandatory viewing for kids, parents, teachers, administrators, school liaison officers. Lee Hirsch chose families in Oklahoma, Mississippi, Georgia and Iowa for the project, and he opens the film with David Long, a Murray County, Ga., father talking about his son Tyler, who had a form of Asperger’s syndrome and suffered years of teasing at school – until he hanged himself at 17. Hirsch introduces us to others, notably 12-year-old Alex from Sioux City, Iowa. Alex also has Asperger’s and endures physical and psychological torture. Alex doesn’t let on to his parents what’s happening. Hirsch obtained surprising access to Alex’s school and bus, and what happens to Alex there is the stuff of every child’s nightmares. If you wonder why East Middle allowed such access: A Sioux City superintendent said the filmmaking was approved because of a partnership with the Waitt Institute for Violence Prevention and that administrators hoped the movie would showcase the successes. Instead, staff comes off as imbeciles. “Bully” raises questions it doesn’t attempt to answer. What about the parents of the bullies? Is there any hope that society can change to become more compassionate? There’s no way to come up with solid conclusions. But at least Hirsch, who tries hard to end on a hopeful note, has insisted on discussion.