A supportive culture on campus is key, but some schools rely too heavily on security technology.
Schools have become savvier about how to prevent attacks in the decade since the mass killing at Columbine High. They have trained staff to spot the signs of a student carrying a weapon and created teams of police and school officials to respond to potential threats.
"It really did create a massive movement in the United States for improved school safety," says Michael Dorn, executive director of Safe Havens International, a nonprofit school safety organization in Macon, Ga. From talks with school leaders around the country, Mr. Dorn estimates that hundreds of planned attacks have been averted: "To me, that's an incredible success."
The concern today is that tight budgets and short memories could mean waning vigilance. Moreover, many schools might be relying too heavily on technology and physical security, rather than tackling the more important challenge of creating a supportive culture on campus.