Student-on-student sexual assault is not just a problem on college campuses. It threatens thousands of kids a year in elementary, middle and high schools across America. Rich or poor, urban or rural, no type of school is immune.

Relying on state education records, supplemented by federal crime data, a yearlong investigation by The Associated Press uncovered roughly 17,000 official reports of sex assaults by students over a four-year period, from fall 2011 to spring 2015.