You really wanna give these teachers guns, AND entrust your child's life (and brain) to them?
There would have to be a volunteers only stringent screening program followed by rigorous training. The ones that survive would be armed. This is going on in many places already. I’d almost go a step further and require firearms proficiency to get a teaching certificate.
Wishful thinking though...the filthy teachers union would have a fit.
If I were the ruler over education in The United States I would do the following...
1. Hire ex-military marks men/women.
2. Pay, in full, for any required degrees (history, math, etc.....upon completion of a 4 year teaching contract.
3. All new teachers must carry in the school.
4. Allow existing teachers to stay, if they feel safe enough to do so.