In an age of rapid change in school buildings, materials and curriculum, classroom teaching has not kept pace with progress in other areas. Continuous re-education is needed to maintain the competence of teaching personnel already in service. One way of providing this instruction is through the use of video tape techniques to demonstrate good teaching practice. Video tape has the advantage of providing realistic demonstrations in different teaching conditions and allowing instruction without disrupting normal school functions. This study investigated the effectiveness of video-taped demonstrations in changing practices and viewpoints of different types of teachers when used in varying ways. Video-taped demonstrations had a positive effect on quality of teaching, the greatest change occurring in those rated as needing the greatest improvement and among the highly motivated. Young teachers learned strategies faster but older teachers adapted learning more effectively to the classroom situation. Principals were fair raters of teacher improvement. A review of teacher training techniques and a bibliography are included. (BB)