There is a big gap between "concept" books written for preschoolers and nonfiction that requires fluent reading skills. The Cat in The Hat's Learning Library books introduce beginner readers to important basic concepts about the world we live in. They provide the critical foundations upon which complex facts and ideas can eventually be built. In addition, The Cat in The Hat's Learning Library shows young readers that books can be entertaining and educatinal at the same time. This is a wonderful series!