How to eliminate school massacres
You could eliminate school massacres pretty nearly overnight by the simple expedient of eliminating public education in America (or in any other large country for that matter). That only sounds stupid until you read a bit more about it...
Public education in the United States as well as many if not most other nations is based on a Prussian model which Prussians adopted after Napoleon wiped them at Jena in 1807. That model was never intended to produce self-reliant people; it was meant to produce cannon fodder and bricks in the wall. That is the underlying problem before you even get to anything like Common Core or leftist indoctrination taking place in schools. Part of the problem is that, increasingly in the near future, the jobs for the robots which that system is meant to produce will be filled by real robots.
John Taylor Gatto is a two time teacher of the year in New York City who left the profession after coming to the conclusion that public education was actually harming children and that there was nothing which an individual teacher could do about it that was meaningful. Taylor there after embarked upon a major study of the history of public education and has become what many considered to be the world's best expert on the subject. He has authored a number of books and numerous articles and YouTube videos on the subject. Items which everybody should read or listen to and watch include these:
As far as I can tell, the best hope for the future in America lies in homeschooling and the neighborhood groups of homeschoolers. A single-family home schooling its children might be problematical but a neighborhood group of families banding together would invariably represent a huge gain over present systems of education. A group of 20 such families banding together would require breadwinners from each family taking a day off work to teach only one day in 20 even if both parents worked in all cases, which would be rare. Kids involved in such a system would be exposed to 20 different major skills and ways of earning money, aside from ordinary educational materials and subjects. And they would be learning from people with real skills and talents and not from people with degrees in "education" with 40 hours of education courses and 20 hours of math, biology, English or whatever.
And amongst the more minor benefits would be this: somebody interested in perpetrating school massacres would not even know which of the 20 houses those kids were going to be in on a given day. It would be awfully hard to do.