In this study a partially-developed category system was modified, and a set of categories was established for describing content instruction used in the classroom by Physical Science Study Committee (PSSC) and non-PSSC physics teachers. Seven physics teachers in the first phase of the study were videotaped to develop the instrument for recording verbal, non-verbal, and verbal-non-verbal content instruction every three seconds. Four PSSC and non-PSSC physics teachers took part in the second phase of the study. Fiv e lessons for each teacher were videotaped and analyzed using the instrument developed. These data were transferred to matrices by a computer program specially designed for the study. Characteristic verbal teaching content processes of the PSSC teacher and non-PSSC teacher appeared. Both groups had significant similarities and significant differences, and different content instruction cycles were proposed. (GR)