Cut the Knot
Cut the Knot!: What Is a Number?
Casual and clear but definitely upper-level discussion of rational, real, imaginary, and several other types of numbers. Links to related sites.
Texas Instruments
Texas Instruments: Bats Triangular
In this activity, students use manipulatives to construct a pyramid. The manipulative pyramid then becomes the basis students use to construct a pictorial representation of a pyramid. The TI-10 is used to show symbolic representation of...