At least five years ago, the elementary school here in Utah where my daughter-in-law teaches fourth grade determined that they would pick up the cost for every teacher who wanted to obtain a concealed weapons permit.
When the principal approached my daughter-in-law and asked her if she wanted to get her permit, she just smiled, patted her purse and said, "Thanks, but no need. I already have it."
Her dad was in law enforcement and she grew up shooting. Of course, her students don't know that she carries, but if I were one of her students, I'd feel very secure in her knowledge and ability to use firearms.
Granted, there are some faculty members who wouldn't feel comfortable with a firearm...and shouldn't be forced to carry one for good reason.
On the other hand, there are some, like my daughter-in-law, who have taken classes, have shot extensively, have their permit, and are very capable handling a gun. So, in my opinion, if that's what it takes to keep our kids safe, more power to them.