"I have been a teacher since 2007, and have taught in two states (Montana and Washington), and in both urban and rural districts. Arming teachers is an incredibly stupid, myopic, and dangerous idea. First, this assumes that the teachers who would sign up to be 'marshals' in their school are mentally and emotionally capable of not being the shooters themselves, which is a pretty damn big gamble. As someone with a history of mental illness, I wouldn't want to be the one carrying and I wouldn't want to know who had the guns.
People who become teachers are generally the kind of people who care deeply and compassionately about students. How would that person be able to hold a gun up to a child and kill him? How do you train a teacher to do that? What special switch would that person need to turn off the part that wants to keep kids safe, and turn on the part that can be fine with killing one? Who trains these teachers? The police? The army? Or are we to assume these teachers don't receive special training at all? Who's at fault if the teacher aims to kill the shooter and the gunfire kills innocent students and staff in the process? Is it the teacher's fault? The school's fault? What if the police mistake the teacher as the gunman and kill the teacher? Whose fault is that? Who will sue whom, and which side will win in the inevitable court cases that will arise from this idiotic idea?
Also, who owns the gun? The school? The teacher? If it's the school, and is like any other piece of district property, that means multiple people would have access to the gun. How would a school or district ensure that no one else uses the gun improperly? Does the gun get left at school when the teacher goes home at night? If so, how is it secured so that it can be quickly and easily accessed when needed? What if a teacher forgets once? How do you keep kids from finding out which teachers or administrators have guns and then stop them from attempting to access them? Students know everything about their schools.
What kind of continued mental healthcare will the school provide a teacher who kills a child? Who pays for it and what will this mean for insurance? How much more insurance will already-strapped school districts have to pay in order to have classrooms filled with guns? How will this impact employee insurance? Will teachers and staff members have fewer insurance options with higher premiums because they work in an at-risk career field?
I have so many more questions, as do most of us, and there aren't any answers. Arming teachers is not a solution, because it misses the whole damn point. Schools are not war zones. Teachers are not soldiers. And any movement to push them into that direction is misguided and will result in more gun deaths, not fewer, and anyone with common sense can see that.
To make these points clearer, once, while I was sitting in a staff meeting, a fellow teacher, who I get along with very well despite our political differences, leaned over to me and said, completely out of the blue, "I get so angry sometimes I scare myself." Another teacher at the table heard him say this as well, and looked at me completely puzzled. He repeated, "I'm so, so angry." It came out of nowhere and had nothing to do with the topic at hand. That guy is pro-gun.
Another time, a few weeks ago, two boys wanted to get into their classroom before school started and the teacher had locked his door while he monitored the hallway. So the boys used a broken protractor to pick the lock to get into his classroom, which was the wood/mechanical shop. They went through the teacher's desk and stole some of his things. The room was filled with large, dangerous machinery. The whole teaching staff was livid when the boys received a slap on the wrist considering what they could have done if they'd taken the knives, saws, etc. out of the room. Imagine if, in his desk, they found a gun instead of candy."