Effectively teaching Earth science requires not only a broad understanding of geoscience topics but also strategies and tools to help students learn. For example, a teacher planning a lesson on the hydrologic cycle should know students' common misconceptions (e.g., groundwater flows as underground rivers), how studying the water cycle can contribute to students' understanding of systems and processes, how to leverage students' firsthand experiences with water fluxes and reservoirs to inform class discussion, and how to assess what students know and understand about the water cycle.
Such knowledge of how to teach effectively within a discipline is called “pedagogical content knowledge,” or PCK. A new service within the Digital Library for Earth System Education (DLESE) seeks to help educators teach more effectively by providing them with access to relevant PCK as they prepare to teach a given topic, issue, lesson, or idea. DLESE (http://www.dlese.org) is a Web-based portal providing access to curriculum materials and information resources for teaching and learning about the Earth and its environment.