Ex military snipers on rooftops during school hours. It works for NY eve, presidential motorcades,etc.Shooters have to be stopped BEFORE they get into the building. Walls, mine fields,I don’t give a darn. Locked doors won’t do it if they’re determined to shoot their way IN. Hell, can parents who have licenses to carry just do a voluntary perimeter to protect their children if the school system won’t? Signup for carpool, sign up for perimeter guard?
Lots of people work from home. Some of them have CCWs. Give a few desks for those people, also allowing CCW in schools, and you have an instant reaction force for the cost of ABSOLUTELY NOTHING.
That’s how easy it is.