Classroom interaction may be described in terms of communication events, i.e., sequences of teacher-pupil communicative behaviors separated from preceding and succeeding sequences of behaviors by natural boundaries. Communication events may be institutional (related to managing the classroom and meeting the expectations of the institution), task (focused on teaching and learning subject matter), personal (centered on the personal needs, goals, and emotions of a pupil, a group of pupils, and/or the teacher), or mixed (containing elements of two or more types). Events may also be identified as individual (interaction between a teacher and one student) or group (interaction between a teacher and several students). These events may be symbolized: I = institutional events; P = personal events; T = task events; M = mixed events. Individual events can then be indicated by placing an "i" after the symbol which appropriately characterizes a particular event. Duration of an incident may be recorded by tallying dots after the symbol at 3-second intervals as long as the event continues. The resultant model (called PIT for "personal,""institutional," and "task") for analyzing classroom communication has been applied to video tapes representing 1,360 minutes of interaction in junior high school classrooms and has yielded some interesting data. It has a number of potential research applications and may be used in combination with other observation systems. (Author/SG)