The e-book is a new type of textbook for self-learning and for use in school instruction. With numerous interactive tasks, the book invites students to explore and get to know the topic on their own. Ideal for learning along with classroom lessons, the book presents important terms and concepts related to fractions. The book was developed at the Technical University of Munich as a collaborative effort of the Heinz Nixdorf Chair of Mathematics Education and the Chair of Geometry and Visualization. It combines carefully conceived educational approaches with the possibilities of modern technology. Numerous illustrations and animations ensure that the book is an exciting gateway to an important topic.