Links Dr. Enger likes-

If you and your students are interested in tessellations, you might find ideas that you can use or modify at these Web sites.

What is a tessellation? (Math Forum)
SHODOR (Computational Sciences)
Online interactive tessellation tool
A tessellation App is available from iTunes- ($0.99) Math Flyer (iPhone & iPad).
Online NCTM Tessellation Creator
Totally Tessellated (Projects for Students by Students)
Teaching with Tessellations
Totally Tessellated (Templates)
You Tube Videos (Just a Sample)
Tessellations: How to Create Them (Preview)
How to Make an Escher-esque Tessellation
Escher Style
Anatomy of an Escher Flying Horse
Anatomy of an Escher Lizard