Open Educational Resources (OER) are learning materials in any medium – digital or otherwise – that are free of cost and carry legal permissions for open use, adaptation, and redistribution. OER can include open textbooks, multimedia materials, test banks, labs, slide decks, discussion questions, assignments, and anything else you might use in your classroom.
OER are one option for instructors wanting to replace expensive commercial textbooks in their courses. Additionally, materials labeled as Affordable Course Materials -- those that are free or low-cost but do not allow for the adaption or redistribution of materials -- can be used by instructors wanting to reduce costs for students while increasing pedagogical flexibility.