Mac Barnett is the author of many picture books including Chloe and the Lion and Guess Again! which TIME Magazine named the number 2 Picture Book of the year. He also writes the Brixton Brothers series of mysteries. Two of his collaborations with Jon Klassen, Extra Yarn and Sam and Dave Dig a Hole have won the Caldecott Honor. He is also the author of The Shape Trilogy, illustrated by Jon Klassen, A Polar Bear in the Snow , illustrated by Shawn Harris and Twenty Questions , illustrated by Christian Robinson. He lives in California, USA. Jon Klassen is the creator of The New York Times bestseller I Want My Hat Back , which was named a Theodor Seuss Geisel Honor Book, a New York Times Book Review Best Illustrated Children's Book of the Year, and a Publishers Weekly Best Children's Book of the Year. He returned with another hat and another thief in This Is Not My Hat , which won the Caldecott Medal and became a New York Times bestseller.