1. a systematic sequence of actions or steps that is approved for use in a potentially dangerous situation, such as a fire, severe weather, or the presence of bombs or guns. In a school setting, these measures are often practiced as a drill to familiarize students with the appropriate procedure.

2. a system in which learners begin with inadequate data and ask questions to gain additional information. The instructor has all the data and reveals a limited amount at the beginning, then discloses more in response to specific questions so that the group can reach decisions. The system is designed to teach the skills of analysis, synthesis, and interrogation that are relevant to problem solving and investigative techniques.