Rice University
Rice University: Cynthia Lanius: Dueling Pinwheels (Geometer's Sketchpad)
An introductory look at the interactive Geometer's Sketchpad in terms of using it to explore rotations, translations, and reflections. Only a beginner's amount of skill with the program is needed. Exploration questions are given for the...
Science U
Science U: Isometries: Rotation
This site from Science U gives good examples of rotational symmetry and some background information about them.