You should be able to shoot anyone that's on your property whether they pose a threat or not. Bet no one would be late with the rent money ever again if the land lord could shoot you a minute past midnight if you're late.
And instead of arming teachers, who are mostly people who can't even shoot and would be useless in a gun fight, we should just give a gun to every single student in the school. It's high time those parasites start handling their own issues instead of expecting us adults to ensure their safety. Plus that'll actually benefit the human race as a whole since the weaker, useless students will be weeded out naturally, just as God intended. The next generation will be the polar opposite of millennials as none of those sensitive crybaby socialists will make it past sophomore year.
And once we give guns to all the kids, well soon be living in an America where every single citizen is walking around strapped 24/7. We could get rid of the police at that point. Hell the military too. But we won't because we all support the troops and we need them to go shoot people in other countries so that we can have the right to shoot each other here.