In the FEMA course on defending v. Active Cowards I took in Oregon's oldest synagogue (NEVER AGAIN!) I was taught to
Lock the door between me and the Coward
If the place I am at does not care enough to have solid core doors, barricade the doorway, and get out of sight
Only after 1) and 2) do I try any active defense.
1. can be accomplished absolutely with a bent or welded piece of lightweight aluminum made in shop class as an exercise by high school students, notched to drop over the door handle on the inside so the Coward cannot see it is in place. If there's no shop class, well, it can be bought commercially: The Device # 2, if installed 34" to 48" over the floor, would comply with fire code, so teachers in a wheelchair could easily use it (and, no, I have no connection to the manufacturer).
2. Since the AR-15 has a .223 small diameter projectile weighing less than a sheet of copy paper (1/7 oz. or less), a thin titanium plate on the outside of a classroom door is a VERY good idea. When the very small bullet hits, it does not penetrate, and some of the fragments can fly back at the shooter, which will hurt. Either discourages the shooter. As Andrew Vachss says, 'Bullies aren't attracted to good fights; they're attracted to easy victims.'
3. Well, active defense? It's obvious the original poster doesn't want it. But, the sheriff of Butler County, Ohio is offering free training. Teachers' other expenses can be covered by a grant from a 501(c)(3) set up specifically for the purpose (and not just in Butler County, mind you).
Now that we've talked about what schools should do beforehand, let's talk about what they should NOT do. They should NOT have a written, verbal, or sub rosa agreement to avoid arresting mentally ill students and former students who have a history of trouble, just to avoid losing some state aid, as Broward County did.
You see, Cruz was known to be banned by the 'school resource' deputy, who watched the coward get out of an Uber and carry the bag with guns into the school, and did not stop him.
But, if it's more important that a school exists to generate revenue, rather than protect its students, then this sorrowful circumstance happens. And, then prosecutors plea-bargain out gun criminals, this becomes more likely.
And, then prosecutors plea-bargain out gun criminals, this becomes more likely.