The Cat in the Hat Knows a Lot About That! has 40 half-hour episodes. PBS Kids renewed it for a second season of 20 episodes which premiered on September 10, 2012. A 20 episode third season is currently in development. Each episode features The Cat in the Hat (voiced by Martin Short), who leads neighbours Nick and Sally, the Fish, and Thing One and Thing Two on a variety of adventures in his "Thinga-ma-jigger", a Seussian contraption that can sprout wings, pontoons, booster rockets, change size, and do just about anything else necessary to further the adventure. The adventures are prompted by a question posed by either Nick or Sally
The Cat in the Hat for the series, including "The Cat in the Hat Comes Back" (1958), "Green Eggs and Ham" (1960), "Hop on Pop" (1963), and "Fox in Socks" (1965). He initially used word lists of limited vocabularies to create these books, as he had with "The Cat in the Hat", but moved away from the lists as he came to believe "that a child could learn any amount of words if fed them slowly and if the books were amply illustrated". Other authors also contributed notable books to the series, including "A Fly Went By" (1958), "Sam and the Firefly" (1958), "Go, Dog.