From NPR News: How To Be The Good Guy With A Gun At School

First, resist the urge to just point it at students. You are a teacher. Aiming at students is a mistake. They’ll expect you to fire and be disappointed if you don’t. To have any authority, you'll have to take one out. Preferably without aiming. Choosing targets is too difficult. The obvious choice is that big pain in your ass of a kid. But he’s kind of funny. Shoot him and the classroom will be dull. That’s no good. What about the girl who won’t put down her phone? Tempting. But she tests well. If you take her out of the equation (so to speak) the whole school suffers. Really you shouldn’t aim. Just let loose. Fire a few times if that helps. Order must be maintained. Respect too. Fire away. In this manner, you can be a good guy with a gun at school. And if anyone argues the point, you know what to do.

(Okay, here's the obligatory note saying that this poem is ironic. It's mocking Wayne LaPierre's suggestions that teachers should be armed. Given all the pressures on teachers, the volatility of students, and the stupidity of Wayne's idea, I'm not a fan of guns in any classroom.)