PBS
Pbs Learning Media: Comparing Volumes of Cylinders, Spheres, and Cones
This interactive exercise focuses on comparing volumes between figures that have the same height and diameter and drawing conclusions based on the ratios of the sizes.
Wolfram Research
Wolfram Math World: Diameter
This site shows what a diameter is, how to find one on a circle or a sphere, and provides the formula to find diameter of a circle or "the great circle of a sphere.
ClassFlow
Class Flow: Spheres Geometry
[Free Registration/Login Required] In this flipchart, students develop an understanding of the properties of a sphere and determine its area and volume.
National Council of Teachers of Mathematics
The Math Forum: Multicultural Math Fair: Srinivasa's Spheres
Straightforward instructional activity that introduces students to pi by letting them measure real objects and solve a challenge problem. Includes instructions and a "Data Sheet" for keeping track of measurements. Available in English...
PBS
Pbs Learning Media: Finding the Circle's Center
In this video segment [3:10] from Cyberchase, the CyberSquad must find the exact center of a circle in order to save Motherboard.