The National Association for School Resource Officers, while still not on board with the idea of arming school teachers, on Thursday offered a tip sheet, of sorts, in case that idea becomes a reality.The do's and don'ts include these helpful bits of advice. Teachers should:"Fire those weapons only in a defensive mode in their classrooms, for the protection of their students. Teachers should not abandon their students to seek out or pursue an active shooter."Receive background screening on par with that conducted for applicants to law enforcement positions."Receive extensive training to include: Maintaining weapon security."Quickly evaluating whether firing is safe and appropriate, based on the risks of injuring innocent victims."Firing accurately in high-stress situations in which deficits in fine motor skills often occur."Receive recurrent training and practice at least once a month."Such a policy is still risky, said the Alabama-based association, which much prefers that trained law enforcement officers do the work. But, they said, the above precautions "will help mitigate those risks."