In this Desmos-ified treatment of a classic math problem, students will first construct expressions with numbers to determine the number of tiles that border a pool. Then they’ll use those numerical expressions to help them write an expression with VARIABLES. Then they’ll put the algebraic expression to the test and see if it helps them find the tiles for lots of pools very quickly.

## Math Textbook with Cat Pictures

Sheldon Axler is a funny math professor and he put his cats' pictures into his math textbook, Precalculus: A Prelude to Calculus.