If teachers want to have guns, then students should be able to carry one as well. I would hate to piss off any teacher in class who is packing heat.
About 25% of my kids do. Thank god they can't shoot for SH**. How do I know? I ask them to demonstrate empty handed their shooting technique. 100% of them hold the "gun" sideways, gangsta style. It's not as easy as you'd think from watching movies or tv. I've had novice students miss a man sized paper target at a distance of five feet completely. It takes formal instruction and range time with an instructor.
I just took a New York liberal, a feminist FORMER gun hater from never laying eyes or hands on any firearm and took her from .22 LR to .45ACP and four inch groups at 30 feet in just three range sessions. Now she's a fanatic.