For some of you, this toy actually brings back bad memories. How many trips did you take to Grandma's, with nothing more than the Little Professor to keep you company on the trip (this was before the days of Iphone or portable Nintendo).
The Little Professor, first released by Texas Instruments in 1976, was essentially the first electronic, educational toy to hit the market. It would give the user three chances to solve a math expression, and then display EEE if they got the answer wrong three times. After every 10 problems, it would display how many first try correct answers were given for the set. The Little Professor is highly collectible these days.