Teaching machines were originally mechanical devices that presented educational materials and taught students. They were first invented by Sidney L. Pressey in the mid-1920s. His machine originally administered multiple-choice questions. The machine could be set so it moved on only when the student got the right answer. Tests showed that learning had taken place. This was an example of how knowledge of results causes learning. Much later, Norman Crowder developed the Pressey idea further.

Burrhus Frederic Skinner was an American psychologist, behaviorist, inventor, and social philosopher. He was the Edgar Pierce Professor of Psychology at Harvard University from 1958 until his retirement in 1974.