Wolfram Research
Wolfram Math World: Dot Product
This math site gives the formula for taking the dot product of two vectors, gives properties of dot products, (commutative, associative, and distributive), how to find the derivative of a dot product. This site has links to several other...
PBS
Pbs: Nova: Super Bridge
Online companion to a NOVA program on bridges. Includes teacher resources, including a class activity through which students construct and test their own bridge,