I love this Geometric Shapes chart shared by Kathryn on Kindergarten Kindergarten! I had to scroll down to find it, but found a ton of great ideas along the way. I also loved her shape museum. (She has lots of free ideas for teaching math concepts.
DIY Line Rocks - to teach pretenders and writers learn words and shapes creativity to create this amazing resource! Cheap and easy to make - perfect for teaching pre-readers and pre-writers shapes, letter and number formation.