... for the school shootings.
It won't stop them all, but it will stop or mitigate many or most.
It doesn't depend on magically figuring out who might crack, or pie-in-the-sky-sometime-by-and-by when we get a perfect mental healthcare system, nor does it infringe on anyone's rights.
Security barriers and procedures in every school, and adequate armed security in every school.
By adequate I mean probably a five-man team per school on average. Some schools will need fewer, some more, but five is a good number for tactical coverage reasons. I might go into where I get that figure later.
The quickest way to stop an active shooter is with an armed defender. The easiest way to DETER a wanna-be shooter from trying it is the knowledge that he'd almost certainly be shot down before racking up his desired body count.
It would make a major impact, along with barriers and security procedures.
But a lot of people resist the idea. Some cite cost. Well, what is your children's safety worth to you?
Some say "OMG, gunbattles in the hallway people will die!" Well maybe maybe not but MORE will die if you let an active shooter have free rein, so get over it.
"OH but we don't want our little darlings exposed to armed guards with GUNS!!" Get over your squeamishness, what's more important their lives or your tender sensibilities... the truth is we all owe most of our safety to armed men of one sort or another, you're just able to ignore it most of the time.
As to cost....
I don't know about the barriers, but we have them at EVERY school in my little podunk town of 3,000, so your school can afford them.
Guards.... the cheapest way would be training and arming willing staff members but for some reason lots of people hate that idea, so we'll look at armed security guards.
$11-15/hour most places for one armed guard. Let's say 15/hr, we want competent well-trained guards. That's 30k/year at 40 hours/week.
About 100,000 schools in the USA. 5 man team per school average. 500,000 guards. x 30k a year. Cost is 15 billion a year.
We send far more than that in foreign aid to countries that hate us. We spend 600 billion on the military and a a couple trillion on social programs, welfare and various domestic spending.
Total expenditures for all schools in the USA is 634 billion. This is a fraction of that, 1/42nd of it to be precise... and it would probably eliminate 90% of school shootings.
Would you be ok with paying 1/42nd more for education so your kids can be ten times safer? Hey it even creates new jobs.
But we won't do it, because special snowflakes hate to admit that the best way to stop an armed murderer is with an armed defender, or people claim its too expensive, or etc.