Better solution.
Every class should have a crew served Gatling gun trained on the door. It builds a sense of teamwork and comradery as students take days of the week for a shift, alternate weeks mean loading or shooting, and having a piece of history come alive will ignite students' passion for their history class, and when Johnny Asshole attacks, it incorporates biology lessions by identifying which mangled piece of flesh was what organ and giving students a pop quiz of determining what was the exact cause of death.
And being such large guns, no kid can steal it from the classroom unnoticed.
I see no downsides.