Does Anybody Remember this?

When I was a kid there were drills we took periodically. When the teacher said “Take Cover!” we were to jump under our desks, as if our desks were going to save us from whatever evil was out there. That’s how you can fool a little kid to do anything.

We were fighting in WW2 at the time.

But that's not what I wanted to talk about.

When somebody comes to school with a gun, why not drill the kids to "Take Cover!" once those words are shouted to them?