Created by the National Science Foundation, the NSDL provides organized access to high quality resources and tools that support innovations in teaching and learning at all levels of science, technology, engineering, and mathematics education. The rapid acceleration of information available via the Internet makes locating high-quality, accurate, and truly useful educational resources challenging for teachers and learners. Educators, in particular, need efficient and reliable methods to discover and use science and math materials that will help them meet the demands of instruction, assessment, and professional development. Over 200 digital library projects and major institutions have contributed to and collaborated in developing NSDL.