If your survival, and the survival of your classmates, relies on your defensive use of a firearm in a classroom against a terrorist; is that not a good reason? 

I hope that you know that my replies are in 100% sincerity with no sarcasm or anything in them. It can get lost in these conversations but I'm genuinely curious about your feelings towards hypothetical situations that make complete sense in my own head. I can't understand where you're coming from if you don't help me. Let's talk this through