What are open educational resources?
"OER are teaching, learning, and research resources that reside in the public domain or have been released under an intellectual property license that permits their free use and re-purposing by others. Open educational resources include full courses, course materials, modules, textbooks, streaming videos, tests, software, and any other tools, materials, or techniques used to support access to knowledge." 
Why use open educational resources?
If you need extra help in a particular topic OER can provide some learning support. Be it through tutorial videos or free e-books. Additionally it gives the opportunity to independently learn on a particular topic of interest.
Educational course materials that have been created by faculty available outside of the institution. Materials can include syllabi, written lectures, assignments, readings, videotaped lectures, and audio lectures.
George Mason University has developed a metafinder that searches the leading repositories for Open Educational Resources. Users can search across all sites or search specific sites. Enter terms describing the information needed to find open educational resources on a topic.
The searches seventeen targets in real-time, instantly returning the top several hundred or so relevant hits from each site. Because it is a real-time search, it can take a bit longer than searches of pre-indexed content; however, as compensation the results returned are absolutely up-to-the-minute for each search target. Additional results continue to trickle in as the search continues running and you begin examining your results.
Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom.
We tackle math, science, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content.