Through the use of simple mechanical instrumentation, Keislar (1959) saw a learning curve develop. The instrument he used was a multiplechoice teaching machine, a converted "Navy Rater," which presented "pages" containing information about rectangles, followed by a multiplechoice question. The pupil responded to the question by pushing one of several buttons. If he pushed the correct button, a new "page" was presented; if he pushed a wrong button, nothing happened. An automatic recording device drew a graph. Perfect learning resulted in a vertical line, and errors made the pen move horizontally. Keislar's finding was that 14 fourth-grade and fifth-grade pupils using the instrument learned the material significantly better than the control group; however, the fact that the instrument can show exactly how the students learned at each step of the lesson and can graph the learning process automatically and instantaneously is more exciting. With instrumentation of this type and other types described by Keislar, large amounts of data can be easily collected which will show learning plateaus, fatigue, weaknesses in presentation, effects of supplemental stimuli, and other variables.