No way! I think that's just asking for trouble.
Teachers have got enough to worry about without having to tote a gun. If I were still teaching, I wouldn't want that risk or responsibility. If they need security personnel, they get them security officers. I want the teacher to be teaching my child, not sling a pistol. Personally, I've met some teachers you wouldn't want turned loose with a gun! I wouldn't dare turn someone lose with one if they haven't been trained to use it. Can you imagine the cost for the weapons, the training, certifications, etc? And I can only imagine what would happen if they weren't properly stored and a child got ahold of one. Then, on the other hand, if you have them stored away and a kid does pull a gun on you, do you have the time to retrieve your weapon??? Probably not. I'd much rather them beef up security with qualified, trained safety staff than to put guns in the hands of people who may not be able to use them.