Just like a fire drill, students and teachers routinely practice what to do if an armed intruder enters their school.
The type of training students receive can vary from district to district, and by age group.
At the Farmington River Regional School — an elementary school in Otis, Massachusetts — principal and superintendent Thomas Nadolny recently got on the intercom.
“The school will now be conducting a lockdown drill,” he announced. “Please go into lockdown mode at this time. This is just a drill. Thank you.”