Please name this book: fictional story teaches math basics?

Question

A teacher loaned me a book in grade school (about 15 years ago) to help me grasp basic math and geometry concepts. I can't remember the title. It was a fictional tale where all the inhabitants of a town were certain shapes and the story helped you understand the differences about the shapes and how they relate to eachother mathematically. It was very short and very creative. Does anyone know the title?

Answer 1

Flatland?
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Answer 2

Flatland