Open Educational Resources (OER) are free for use in non-profit educational context. They fall into one of three categories:
1) Content-based OER: subject-specific learning objects, lessons, activities, digital books and references available for use, and sometimes for remixing and publishing.
2) Technology-based OER: technology tools for the development of learning objects and student interaction. Oftentimes these are also Open Source technologies – meaning that, as well as being free to use, the actual code behind the technology is freely available for use and modification.
3) OER Licensing: the modern copyright concepts that allow individual educators and educational institutions to publish their content for open use while still retaining some rights or control use regarding repurposing, modifying, and republishing. The definitive resource for this type of licensing is Creative Commons.
Our Diigo list contains OER for all categories. Check it out here at: www.tinyurl.com/Tri-COER