It’s all about stimulus and response.  Developed by behavioral scientist B.F. Skinner, the machine—and its many iterations– made it possible for students to move through lessons at their own pace.

The machine would pose a question, then offer a reward, usually in the form of encouragement, for answering correctly. (Pavlov’s dog, anyone?) Skinner also advocated using machines to teach and reinforce good classroom behavior.

The  “reward” approach was used heavily in language labs and also laid the foundation for computer instruction.  The below video shows Skinner making his case for why educators need the machine.