Happy Pi Day to You! All About Measuring Circles (Cat in the Hat’s Learning Library) by Bonnie Worth, illustrated by Aristides Ruiz and Joe Mathieu. Happy Pi Day to You features The Cat and the Hat who helps introduce circles and pi to a few children using rhymes (which follow the ABAB pattern). A few of the rhymes are forced, but it does read well as a read-aloud book.
The Cat teaches where circles can be found; how to make a circle with two sticks and a string; the definition of diameter, radius, circumference; and how to find pi. The last third of the book talks about pi history and who helped “discover” pi. A glossary and list of websites to visit then follow the story.
Students can use the concepts from the demonstration in the book to make their own circles using pencils and string.