ABSTRACT
Large classes, inadequate time, limited equipment and facilities, and a typically wide range of student abilities all work against a teacher who attempts to plan and implement individualized learning for students. Personalized System for Instruction (PSI) was developed by Keller and his graduate students at the University of Sao Paulo, Brazil, in the early 1960s and refined a few years later at Arizona State University. The PSI model is designed to allow each student to progress at their own pace through a sequence of prescribed learning tasks. The teacher need only be aware of which tasks will be attempted in the upcoming lesson so that they can provide the necessary equipment for student engagement with them. The responsibilities of providing students with information about class management, learning tasks, and assessment are carried out with a course workbook and instructional media. A science of human behavior is based on these and other relationships between a person and their environment.
