This solution is a bit ...

.
... more involved than I would like to see, but it's better than what's been floated:

Putting guns in schools has struck many as a radical suggestion since the Sandy Hook massacre. But in one rural Michigan township, the police chief has come up with a thoughtful, serious plan to do just that.

During his 33-year-career in law enforcement, Victor Pierce has seen the bodies of murdered children, and he’s struggled to reckon with it. After Sandy Hook, he felt compelled to do something, he says. So he decided to invite teachers and school administrators to participate in the reserve-officer-training program. After they’d completed the class, Pierce would swear them in as volunteer reserve officers, and if the school district gave its blessing, they could carry concealed weapons on campus.

I don't believe that teachers should have to be reserve officers (if you've got a state-issued permit, you should be allowed to carry - anywhere) but if that gets defensive firearms where they need to be, then do it.

And to hell with what the school district wants; if reserve officers are allowed to  carry in a school, it's none of their concern.

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