Well, the phrase that comes to mind is the 'Those who can't do, teach'. Honestly, considering some the idiotic socialist things that come out of some teacher's mouths today, I'm not sure I'd trust them w/ guns!
If they feel the need to carry, via say, a CCW like mentioned earlier, then I think they should be free to do so. And I'm all for teachers and schools being able to discipline students as needed, rather than being hamstrung by a crazy system that holds them responsible, but gives them no authority as they are currently.
Before you think I am against teachers, or look down on them as a whole, I'm not. My better half just finished her teaching degree in elementary education. But I think teachers are a little like cops, in that while there are an awful lot of good ones out there, and a lot more that at least have good intentions, there are still plenty that are either lazy, corrupt, or otherwise completely unworthy of the responsibility placed upon them. And like cops, these are the ones that seem to 'jump out' at a person when looking at the group.
Sorry for the rambling. Just had to say something, though.