Because one can only see the new through the lens of the familiar, children's concepts of the world and things are central. Teaching can only be effective if the domain-specific prior knowledge of learners is taken into account when planning and supporting learning processes. This volume addresses the core question: What do children think about the world and its things? The present volume discusses fundamental questions regarding the significance of children's concepts for subject teaching, as well as the field of nature, human beings, and society. The 13 thematic contributions present the current international research status on domain-specific preconceptions of primary school learners and implications for curriculum development. Students, teachers, trainees, and educators in subject didactics thus receive foundational insights for preparation and implementation.