Well, SJL is obviously totally nuts, but I think a plain and simple bar that could be dropped across the classroom door to KEEP THAT DOOR SHUT would be very fast to implement, and effective. A "shooter" confronted by such a barrier is then limited to firing blindly through the door/wall/window in door.
Difficult to impossible to "shoot out the lock".
Eventually the door should be bulletproof. Put bookshelves/chalkboards along entryway walls on the sides of the door.
Hmmm. You may be on to something here.
Frankly, I'm not enthusiastic about arming the teachers. I've met a lot of them, and didn't entrust my kid to their care. Never mind, trust them to carry safely around my kid (or anyone else's, for that matter).
But the concept of a simple door bar should be easy enough for even the dimmest of them to grasp.
Each classroom could have a small hardened shelter built into it, where the door is barred from the inside. Communication means within the shelter can relay info, both when under attack or for informing all is under control.
It would be terrifying having to flee to such a shelter, but cement blocks can take bullets far better than flesh.
But don’t classroom doors open outward?
Only problem with your solution is that classroom doors open OUT. It’s a fire code. In public places, doors must open out, so if people need to evacuate quickly they don’t get jammed up in doorways.
Pretty low tech to even bump the door braces down if a lock down alert is activated. Long bolts and riveted steel plates on the doors would slow most down enough to give the school militia time to box him in and cap his a$$. ;-)
Every classroom I've ever been in had windows, and they're not bulletproof. So I guess we need a couple hundred billion to change out the glass as well.