This article was written by John Woestman of the Builders Hardware Manufacturers Association (BHMA) and recently appeared in Locksmith Ledger.
A variety of specialized locks are designed for traditional use in schools on classroom doors. The classroom lock’s function type is unique in that the lock can only be locked or unlocked from outside the classroom by using a key (usually held by the teacher, administrators and custodians). Since this type of lock must be locked from outside the room, it is intended to make it difficult for mischievous students to lock the teacher – or other authority figures – out of the classroom from the inside.
Following the tragic events of Columbine High School in 1999, the classroom intruder lock was designed to allow a teacher to lock the classroom door with a key from the outside or the inside of a classroom. As this type of lock allows the teacher to use a key from inside the classroom to lock the outside lever (with the door closed), it can prevent unauthorized ingress through the classroom door—a functionality which can be important in the event of an emergency.