Mapping Our City worked with students and teachers in three middle schools in Boston to explore their urban environment. Students used a set of software tools called Geographic Information Systems (GIS) to display, manipulate and analyze data on computerized maps. They collect their own data, as well as using satellite images, aerial photos and commercial data sources. They prepared interactive, computer-based maps of their own neighborhoods, including housing, businesses, natural features and other resources. One group of students focused on using GIS to monitor water quality in the Muddy River, an urban river that flows through Boston. We believe that the combination of real-world investigations and the cognitive power of interactive visualizations helped the students develop deeper understanding of key concepts of science, better visualize the inter-relationships of natural and human forces in their environment, and develop skills of inquiry and investigation.