A selected list of large OER repositories.
Open Educational Resources (OERs) are freely accessible, open-licensed learning materials that can be downloaded, re-used, shared, and adapted to individual classroom use. This definition from OER Commons sums up the breadth of material available:
'Open educational resources are teaching and learning materials that are freely available online for everyone to use, whether you are an instructor, student or self-learner. Examples of OER include: full courses, course modules, syllabi, lectures, homework assignments, quizzes, lab and classroom activities, pedagogical materials, games, simulations, and many more resources contained in digital media collections from around the world.'