'Selected teachers' would be human, too ... ie can go nuts just like anybody else.
sure - and they have unlimited access to our kids. So please cite some incidence of teachers going on a killing spree with tools they have immediately available. Maybe alcohol and bunsen burners for molotov cocktails, or running groups of kids over with their car in the parking lot.
There's this weird notion that possession of a firearm makes you subject to go off at any time. Folks think the firearm causes the action. If teachers were so apt to "go off" we'd be having lots of killings with everyday available items in the school - but does that happen regularly, or even at all? HMMM. Maybe it's not the presence of the firearm that makes the killer after all. Trust me, if you took all the firearms from everyone, these nuts would resort to bombs / fire for mass killings. So then you need to ban glass bottles, gasoline, and rags. Oh, and we'll need to ban cars, they're pretty dangerous in the wrong hands too, never know when a driver might "go off".
C'mon man think - the gun never drove itself to school and pulled it's own trigger. it's not the gun, it's the idiot who thinks killing lots of defenseless people is cool. Steve