Have you ever heard of the National Science Digital Library? If you teach subjects such as science or math to students through English, you may find this service helpful.
The National Science Digital Library provides high quality online educational resources for teaching and learning, with current emphasis on the sciences, technology, engineering, and mathematics (STEM) disciplines—both formal and informal, institutional and individual, in local, state, national, and international educational settings.
Searches by subject, education level, resource type and standards are available. You can also browse by provider and by collection shared with the NSDL.