Being completely unpopular here, NO! it is NOT the teacher's job to ensure a student's safety. It is THE SCHOOL's job, meaning principal, facilities manager, other OUTSIDE the classroom personnel (maybe not custodians) to ensure that teachers' can TEACH, which is their job.

I'm a professor and I teach students how to be teachers....it is not their job to protect students. Now hear me now, teachers will, teachers do, and yes, keeping kids from harm generally is a teachers' job, meaning don't let other children or adults hurt kids...yes absolutely. But too much has been expected of teachers like, parenting, feeding, instilling a political agenda, teaching belief systems and sexuality, socializing and keeping safe from bullies, while making sure kids can read, write and do math. WHAT are the administrators for? What are parents for? and now talking about training teachers to use guns to deter an active shooter?

As someone who teaches teachers, no wonder instructors are quitting.