Not to mention that if all the classes do the same thing the ruse is ineffective, you won't fool anyone that ALL the classes are empty.

That was always just stupid.

I don't know why no one's thought to booby trap the school. Lethal or not. If I were a teacher, I'd set up a way to electrocute an intruder. I'd also secure an escape route, through the ceiling if I had to. And I wouldn't tell anyone.

You make an interesting point. Nobody wants to be the turkey in a turkey shoot and that's just what most of these strategies do. Prevent meaningful evasion attempts and fail to respond to threat. If we're not going to address the mental health crisis or put limits on guns, your choices in life become being a turkey primed and waiting for slaughter, or learning to respond and defend in kind. Sitting in the dark is no answer.