If you were asked by a school for recomendations for arming teachers...

The only viable option, that will be carried often, is a pistol of one's choosing. It should be concealed because the goal is to maintain the element of surprise. Which basically rules out long guns.

There are other issues with long guns that make them less than ideal choices. For responding officers who have them in their vehicles is one thing, but the on-site logistics get really messy in a hurry. It's a bad in practice option. At least with how most places have implemented it.

I work in a school district, and if I could carry I would have many options. I'd start with my 4" M2.0 Compact and consider the larger full sized guns. I'm actually equally accurate with the Compact as my 5" full sized sister gun. Then again I'm not exactly having issues with the 10MM either. I could bring in the revolvers too. Hot .357 loads would be good.

The teachers are there to teach, not walk around with a rifle slung over their shoulder. Give them mandatory training, and allow them to carry in a manner where the gun is concealed as to not be a distraction.

Regardless of whether they have a gun or not, all teachers (and as a public employee myself) and all public employees who are around the public or interact with the public, should be trained for basic first aid and stop the bleed care. The amount of city/county/state employees that are out driving around in the course of their duties, like the dudes who are fixing the plumbing in the streets, paving the roads, inspecting the restaurants, etc are huge. Even forgetting about active shooter situations, I've rolled up on everything from car accidents, people passed out on the sidewalk due to medical issues, people overdosing, etc and would love more training and equipment to help.

I have known lots of teachers, including several close relatives. I wouldn't trust any of them with a Swiss Army knife.

My recommendation has always been to recruit retired cops and military veterans, organized as a volunteer force, each participant agreeing to perform two half-day shifts per week. Preliminary background checks, orientation training including refresher training in use of force, and semi-annual qualifications with the handgun of personal choice.

Two officers assigned per shift, one covering main entry and one patrolling perimeter, changing off each hour or so. As little interaction with administration and teachers as possible, they will be there without questioning or complaints. Plain clothes, maybe a distinctive vest as a means of identification and cover garment for the hardware (avoid giving liberal arts majors a case of the vapors).

Volunteers, no wages or direct compensation, but the school district covers each officer's monthly health insurance (no, that is not free in most cases) and provides liability insurance and workers compensation coverage.

Many folks would be surprised how many of us old grampas and grandmas would step up to protect everyone's children.

We have hundreds of thousands of fully trained and qualified retirees who would gladly step up to do the right thing.

Potential school shooters would quickly learn that their intentions will require that they face more than children and staff, maybe walking right into a couple of folks who have been there and done that many times before.