I know an extremely fit 51 year old female teacher who cannot assuredly physically control the boys in her class. If they want to walk out the door, she has to let them. They can take her down.... in 3rd grade.
So, if guns are to be in classrooms, we'll need some really good security on them. Finger-print enabled locked boxes, or the like.
Whatever it takes. I’m sure there is a way to secure firearms to be inaccessible to students. But if you have to run to the office to get your defensive weapon, it’s too late