National Science Digital Library

TheĀ National Science Digital Library is the National Science Foundation’s online library of resources and collections for science, technology, engineering, and mathematics (STEM) education. The NSDL contains 123 collections and over 125,000 records (metadata, paradata, and annotations), in addition to other supporting user and technology services. New resources are added to the Library every week. Use of the NSDL website and related search and reference services is completely free, as are the majority of the resources discoverable through NSDL.