I am NRA. Before you demonize it you should look at what it actually does. It promotes safe gun use, training, even the background check was a NRA idea. They do support some politicians, but so do a lot of other lobbies. I have talked to some of the political activists and they want to get ALL guns away from ALL the people, leaving only the government with any power. The Kent State thing tells it; an armed government running rough shod over the rights of people who disagreed with the politicians.
The US is not the only place where shootings take place, and if you look at per capita it is even down the list.
I just saw a meme of two signs; one saying "gun free zone", the other "armed and trained personel on duty". Which place is going to be hit?
Nobody is trying to arm all teachers, but if a few were allowed it would make a would be shooter have to think; metal detectors, police, and such would be nearly impossible to pull off. I know some government buildings have security, but doing that for all the schools is a far greater task.