Learn about different shapes and how they work.  For preschool to kindergarten.

Books
Exploring Shapes by Andrew King
Bear In A Square by Stella Blackstone
It Looked Like Spilt Milk by Charles G. Shaw
Shape Up! Fun with Triangles and Other Polygons by David Adler
Shapes, Shapes, Shapes by Tana Hoban
What is a Triangle? by Rebecca Kai Dotlich
What is Round? by Rebecca Kai Dotlich

Realia
Geometric Shapes activity book
Rubber Shape puzzle
Shape Bingo game
Shapes puzzle
Form Fitter
6 Shape cutouts
Tactile Shape Color Boards
Feel and Find mystery bag
Shapes Match Me game
Bag of Wooden Shapes
Box of Shapes (contains square, circle, and triangle pieces)

Book & Cassette
Shapes in Action

Video
Changes, Changes