This project is developing and evaluating a Strand Map Service to provide an interactive and flexible interface to educational resources in the National STEM Digital Library (NSDL). Strand maps depict the interrelationship of science learning goals based on the AAAS Benchmarks for Science Literacy and the NRC National Science Education Standards. These learning goals describe what learners should know, or be able to do, at key stages in their education. The service enables educators and learners 1) to discover educational resources that support the learning goals, or benchmarks, articulated in the strand maps; 2) to browse the interconnected learning goals in the strand maps; and 3) to enhance their own content knowledge by using the service to explore important background information on the learning goals, such as prior research on student misconceptions.