Smithsonian Institution
National Museum of American History: Slates, Slide Rules and Software
Did you learn to calculate using a 7-foot-long slide rule? Did you learn about the properties of numbers using brightly colored Cuisenaire rods? Ever wonder who invented the graph paper you used in geometry class? Go back to the...
National Council of Teachers of Mathematics
Nctm: Illuminations: Making Triangles
Understand the mathematical meaning of a triangle and the idea of congruence, or sameness, in geometry.