http://www.geocities.com/Paris/Rue/1861/etyindex.html

This is the definitons page

http://jwilson.coe.uga.edu/gsp.lesson.folder/gsp.lesson.html

This is from a professor at the University of

Georgia

http://math.rice.edu/~lanius/misc/

Deuling Pinwheels-tesselations

http://www.wpunj.edu/icip/itm/Lessonpl/sketch/coutts/coutts.html

Another site with Lesson plans, Segment

Addition etc