This 9 page M.C. Escher packet includes everything you need for drawing impossible shapes and tessellations: 
An art analysis, students pick their favorite Escher artwork from the page included and answer specific questions about it
A Compare and Contrast worksheet where students answer specific questions about 2 of Escher's pieces. These have been particularly picked because they contain an impossible shape and a tessellation.
4 step-by-step instruction sheets for students to draw the shapes including a cube, triangle, hexagon and star
A worksheet with some of Escher's tessellation designs and a step-by-step instruction how to create their own, starting with a square. I suggest walking students through this as a demo, etc. The last page includes original student examples of tessellation designs.
 
Great for lesson introduction, sub plan, etc. — I use this along with my study on Optical Illusions grades 5-12.