Do you recall the 7-foot-long slide rule that used to hang above the blackboard in math class? Ever wonder who invented graph paper? Have you worked with a geoboard? The Smithsonian's National Museum of American History has put together an exhibit displaying tools used to teach mathematics in the United States from the 1800s to the present. The accompanying Web site provides a capsule history and images of various teaching aids used over the years.
Go to: http://americanhistory.si.edu/teachingmath/