THERE ARE SO MANY ISSUES YOU START GETTING INTO.

Often, schools react reflexively after high-profile school shootings, snapping up technologies and services as a symbolic gesture, Lavarello said.

“Right now, you feel sorry for these kids who have lost their lives, and you’re searching for something fast, anything,” he said. “The principal wants to tell the parents, ‘Look, I have metal detectors and armed guards.’”

But products like a folding shield with straps called the Bodyguard Blanket and a remote-controlled pepper spray system are often far from infallible, Lavarello said.

He said his team had recently conducted a safety assessment at a school near Denver that had spent US$600,000 fitting every window on campus with bulletproof film. Administrators had not realized that the film would prevent students trapped inside from breaking the glass to escape in an emergency.

Advocacy groups focused on school safety, many of them founded by relatives of shooting victims, increasingly try to offer guidance to school administrators in the form of checklists and updates on local programs. The National Institute of Justice, a government agency, administers a program to test the effectiveness of commercially available body armour.

Erroll G. Southers, a public policy professor and the director of the Safe Communities Institute at the University of Southern California, said that all schools should at a minimum have their campuses assessed for safety risks.

He even proposed that insurance companies reward schools that do safety assessments with a reduced premium.

“Schools should be treated like critical infrastructure,” he said.

Some campuses are starting to rely on outside help, taking donations from families, neighbourhood businesses and local rotary clubs. One company pledged to donate proceeds from its bulletproof backpacks to Parkland victims and their families.

Several bills seeking to fund school safety efforts are currently winding their way through Congress.

Sandy Hook was rebuilt in 2016 using a US$50-million gift from the state of Connecticut. It has bullet-resistant windows