The term "lockdown" is actually used any time all students are supposed to be in a classroom and no one is allowed to leave. A "Code 300" is specific to intruders. These can also come in the form of a drill. Students have to stay "locked" in the room during a drug search, because if a student did have drugs and was allowed to leave the room, he/she would probably dispose of them after hearing there was a "shake down." It's kind of meant to be a surprise so that they don't have time to get rid of anything. It is scary to think that someone could be threatening the life of your child, but it is good to know that these "dramatic lockdowns" are there to help protect our children from intruders AND drugs!