It's not a perfect solution, but it is far superior to any of the stupid suggestions most people are suggesting.
Yes, Arm the teachers, and kill these bastards that show up at schools with intentions of shooting people.
nothing new here-
SCHOOLS ARE GUN ZONES in 1800
In 1800:
Children of the present day would be somewhat startled to go to school attended by large dogs, to keep off the bears and other wild animals, to study all day by the crackle of the great fire and back logs, to hear the howling of wolves at rollcall, and see the teacher take from its resting place over the door, a trusty rifle to guard the way home. Such were the first schools in 1800.
Periwinkle, The Sentinel, Feb 21, 1874 [Ticonderoga Sentinel, Ticonderoga, NY]