Using guns as a deterrent to potential gun violence isn't going to solve anything.

Its like back in the Cold War, building more nukes isn't going to prevent nuclear war but increase the intensity of it should it actually take place.

Also, I wouldn't trust 99% of teachers with a gun to protect me or anybody.

I've got teachers old enough to be my great-grandparents so they'll be super helpful when in a dangerous situation like a school shooting.