A method of teaching that usually is characterised by. (1) The goat-your-own-pace feature, which permits a student to move through the course at a speed commensurate with his ability and other demands upon his time. (2) The unit-perfection requirement for advance, which lets the student go ahead to new material only after demonstrating mastery of that which preceded. (3) The use of lectures and demonstrations as vehicles of motivation, rather than sources of critical information. (4) The related stress upon the written word in teacher-student communication; and, finally. (5) The use of proctors, which permits repeated testing, immediate scoring, almost unavoidable tutoring, and a marked enhancement of the personal-social aspect of the educational process (Keller, 1968, p. 83). Also known as the "Keller Plan," after its originator.