General Sciences Textbooks (Licences vary)
A collection of open textbooks on different science-related topics.
Applied Math and Science Education Repository (AMBER) (Licences vary)
A collection of educational resources and services on topics related to applied math and science.
PhET Interactive Simulations (Open Source – CC BY)
The PhET Interactive Simulations project at the University of Colorado Boulder creates free interactive math and science simulations. The site is available in a number of languages.