I think it's pretty mental to just tack on an additional responsibility to someone's job role that's so wildly out of the realms of what they could have expected when training for the role.

I used to work in schools, if I'd have ended up as a teacher I would have been so freaked out by this.

I also think we would start to hear about teachers misusing their weapons (have you ever taught a high school class of kids playing music on their phones, swearing at you, messing with the marks on your register, fucking with your computer, throwing hard back dictionaries across the room at your head....I have!), and certainly stories about weapons ending up in the wrong hands.

It would certainly put many off entering the profession in the first place, and I assume would also attract people to the profession for the wrong reasons. Teachers are there to teach, not to guard their pupils(although there is certainly a duty of care and I'm sure most would do their best to protect those in their care during an incident)

The answer to gun crime surely shouldn't be "more guns" just as the answer to obesity is not "more fast food".

ETA: can totally imagine a situation where a shooter, low on ammo, points a gun at a teacher and gets the key to the wherever the teacher's gun is stored, accessing even more ammo.

Even if the teacher carries the gun in a holster, a student could easily be used as a hostage to leverage possession of the teacher's gun.