just as dumb and unworkable as arming teachers

[Luddly Neddite]

Bulletproof white boards act as shields

... a handheld white board for classrooms that can stop a bullet from a handgun fired at point-blank range...

...The 18-by-20-inch, 3.75-pound white boards are meant to slip unobtrusively into the classroom as a teaching tool while being large enough to cover the head and torso. Each has three rubberized handles on the back, handy for a teacher to carry. In an emergency, the user can slip a forearm inside the handles, and it becomes a shield...

"Oh, crazy person with a hundred round drum, please wait while I (a)unlock the closet, get that gun that I think I left on the top shelf and then get some ammo and load the gun and ... or, (b) oh damn, where the hell did I put those two shields they gave to each classroom and how the hell do I pick which of my 30 kids gets to hide behind it and where the hell are we supposed to go?"

OR,

they could put a deadbolt lock on the inside of every single door in the school. One announcement to shelter where you are covers the entire school in a couple of seconds and doesn't depend on having defense at the exact place the crazy person decided to start shooting.