2. M. C. Escher Tessellations
http://www.mcescher.com/
3. A tessellation is a pattern made
using congruent shapes.
http://gwydir.demon.co.uk/jo/tess/hexagon.gif
http://www.geom.uiuc.edu/~demo5337/Gr
oup4/eq.tri.grid.1.gif
4. A congruent Shapes are shapes that are
exactly the same in size and outline.
http://missy240.edublogs.org/files/2011/08/congruent-turtles-162npfz.jpg