Discover Series Books for Babies & Toddlers Every princess needs a castle and every knight needs a fortress to defend. In this Discover Series book, young children can learn the proper terminology for castles and explore the crisp and clear photographs with simple titles. Used as a jumpstart for interaction, Discover Series Picture Books are a great way to introduce new images, words and ideas to kids. Use this photo dictionary as a learning tool. Each photo has a clear title beneath it for identification. Language learners, children, and people looking to build their vocabulary can use this simple book to learn new words.