Because of the need to explore the dimensions of the teaching-learning process, this paper presents a systems' conceptualization of this process, describes an instrument for measuring the major classes of teacher-pupil influence behavior, and discusses data collected with the instrument. Teaching is viewed as human interaction within a series of inter-relationships (or system) among persons. A model using only those significantly relevant relationships is selected as the focus of any particular investigation. The foci of the present study are: (1) subject matter instruction, (2) control, (3) routine-administration, and (4) organization. Behaviors observed in teaching interaction fall into one of those categories as well as one of four functions: (1) exposure to information, (2) precipitation of a response or action, (3) evaluation of a subject matter response or a classroom management move (feedback), or (4) recognition of an idea or affective feeling. Interactions are coded in a three-stage sequence: (1) stimulus demand upon the teacher, (2) response, or lack of it, by the teacher, and (3) pupil response to the teacher's move. (BP)