On-board cameras showed it all.
In a South Carolina school, the principal called in the cops after these same cameras recorded drug deals going down.
For better or worse, as CBS News Correspondent Mark Strassmann reports, in American schools security cameras are now almost as routine as backpacks.
And what really goes on during the school day is becoming an open book.
Walk into any classroom in Biloxi and your every move is being watched. In fact, in all of America this school system may be unique. There's a camera in every classroom.
At Michel Middle School, what teachers can't see, cameras often can.
"It's like a second set of eyes watching them," says teacher Amy Thibodeaux. "It's like a second teacher in the classroom."
Now, in classrooms, in hallways and outside the school, most student behavior here even meets the standards of principal Pam Manners.
Manners can check in on any classroom, any time. When students know they're being watched, she says, they act as their own monitors.
"I am able to deal more with the business of learning, and not the business of behavior," says Manners.
Critics say it's constant scrutiny that gives students the wrong lesson.
"Keeping a camera on them every day of the week is teaching them that being watched is OK and possibly Big Brother is good," says Jill Farrell, of the Free Congress Foundation.
But parent Janet Pugh believes school cameras help protect her daughter Emily - protection from trouble Roy Balentine wishes he had.
"I was of the mindset that this won't happen here," says Balentine.
Balentine was principal at Mississippi's Pearl High School when one student killed two others and wounded seven more. He now sells camera systems to school systems.
There were no cameras at Pearl.
Would they have helped?
"I can't say that they would have prevented the situation from happening, but I think there are certainly situations now that we have seen where cameras very possibly could help prevent a situation," says Balentine.
Or help preserve a situation on videotape.
Sometimes with a warning as clear as a school bell.