The best way to shield a school from a gunman is to have a metal detector. Or doors that can be remotely locked. Or Twitter-trawling bots looking for threats. Or bulletproof clipboards, whiteboards and backpacks.
"With Schools as Targets, Security Outfits Flourish" is from the March 04, 2018 Business section of The New York Times. It was written by Tiffany Hsu and narrated by Keith Sellon-Wright.