World101 from the Council on Foreign Relations
World101 is a growing library of free multimedia resources divided into units and modules. "Through its entertaining, interactive story-telling, World101 makes complex international relations and foreign policy issues accessible to learners..." Includes Teaching Resources for instructors.
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OER Repositories
There are a multitude of OER out there to choose from, including textbooks, courses, multimedia, data, and supplementary materials. These can be found by searching regular search engines (like Google) by using certain keywords but it is much easier to find them through dedicated OER repositories or websites. The examples below are just a sampling of such repositories and websites.
Many universities have research guides related to finding OER and provide lists of various repositories and resources.