A curriculum-linked professional development approach designed to support middle level science teachers' understandings about tectonics and geospatial pedagogical content knowledge was developed. This approach takes into account limited face-to-face professional development time and instead provides pedagogical support within the design of a Web-based curriculum with extensive teacher support materials. This paper illustrates how curriculum design can provide teachers with supports for content (e.g., tectonics) and geospatial instruction with Web GIS. The effectiveness of the approach is presented with a focus on how the curriculum implementation of the Web GIS tectonics investigations and the curriculum support materials provided teachers with the professional growth required for successful curriculum implementation.