Classroom lockdown drills have become commonplace practice in U.S.

Classroom lockdown drills have become commonplace practice in U.S. schools, where 74 shootings have taken place since Sandy Hook, and teachers live with the fear that violence could enter the halls at any time. Now a group of educators has designed “The Sleeve,” an invention that easily locks classrooms from the inside, something that is not currently possible and might help to protect students—without having to replace every door in schools. (Fast Company, Quartz)