In order for a resource to qualify as an Open Educational Resources, users should be able to:
(This material is based on original writing by David Wiley, which was published freely under a Creative Commons Attribution 4.0 license at: http://opencontent.org/blog/archives/3221)
OERs can come in a variety of forms; for example: open textbooks, videos, courseware. Here are a few sites to get you started: