overall: 1 in x 3 1/2 in x 5 in; 2.54 cm x 8.89 cm x 12.7 cm
electronic calculator; Handheld
Introduced in mid-1976, the Little Professor is a non-printing electronic calculator modified to present simple arithmetic problems. A correct answer prompts another problem on the eight-digit display. An error delivers the message, "EEE." The colorful keyboard shows a professor with whiskers and glasses. The red light-emitting diode screen, in combination with the top of the instrument, looks like a mortar board.
This example has buttons that allow one to set the level of problems, as well as an on/off button on the front rather than the side of the machine. These features were introduced in a version of the machine made from 1978 onward.
P. A. Kidwell, A. Ackerberg-Hastings, and D. L. Roberts, <I>Tools of American Mathematics Teaching</I>, Baltimore: Johns Hopkins University Press, 2008, pp. 261–262.