The classroom intruder lock was developed to achieve an extra level of security for students and teachers. With a classroom intruder lock, during an emergency situation a teacher is able to lock the outside lever from within the classroom . The exterior lever is locked by operating the interior lock cylinder, unlike standard classroom function locks that require the exterior lock cylinder to be operated in order to lock or unlock the exterior. During an emergency situation, having to open the door in order to lock it is not a good idea. For the intruder classroom function locks as well as the standard classroom function locks, the interior lever is capable of retracting the latch at any time.