Next, I used a lesson created by a "Math Guru" in my district. I have attached the link to her posting of the same lesson here We began by reading The Greedy Triangle, by Marilyn Burns. This cute story follows a triangle who unsatisfied with his shape, requests the local shapeshifter to add another side and angle to him so that he can become a quadrilateral. This pattern repeats and as he continues to add more angles and sides we see him transform into pentagons, hexagons, heptagons, octagons, nonagons, and decagons.
While I read the story, my students explored making the various shapes using large fuzzy pipe cleaners (they were a real hit!). These pipe cleaners can be found at Michaels. They absolutely loved this activity. As they continued to work with the materials, adding sides and angles, they demonstrated a concrete understanding of 2-D shapes.