Students often choose to borrow textbooks from the library or rent them from the bookstore in lieu of purchasing the textbook. For those that do purchase textbooks, many attempt to regain their money by selling the books back to the bookstore or online after the course is over. OER are free and available. Students can take their materials with them after class ends, which means that they will always have access to learning materials for future use.
Textbooks and educational materials are often covered by stringent copyright restrictions, which does not allow reuse in other contexts or modifications or derivations. With OER, students and instructors can re-use and re-purpose the materials not just during the class, but in the future as well.