We've discovered the cause of ADD.

Farmington Police and school district officials are investigating several junior high teenagers who swapped nude photos of themselves over cell phones.

This is the third time this school year that Farmington schools have caught students "trading photos of their genitals and other nude shots," says a spokesman for the Davis School District.

"Imagine being a teacher trying to teach a class and you've got students sharing inappropriate photos of each other," the spokeman says. "You're not going to have the attention of the students."