One of the subjects is Alex Libby, a twelve-year-old seventh grader at East Middle School, in Sioux City, Iowa.

NEWYORKER: Kids at Risk

Another expert in such cruelty is the film's central character, 12-year-old Alex, a gentle middle-school student in Sioux City, Iowa.

WSJ: Bully | The Island President | Wrath of the Titans | Cruel Kids, Weakling Schools, Hard-Hitting 'Bully' | Film Reviews by Joe Morgenstern

Hirsch and Lowen film him being clobbered on a school bus and threatened obscenely in front of his school, in Sioux City, Iowa.

NEWYORKER: Bully