“Open educational resources” means high-quality teaching, learning, and research resources that reside in the public domain or have been released pursuant to an intellectual property license that permits their free use and repurposing by others, and may include other resources that are legally available and free of cost to students. Open educational resources include, but are not limited to, full courses, course materials, modules, textbooks, faculty-created content, streaming videos, tests, software, and any other tools, materials, or techniques used to support access to knowledge. --California Education Code, Section 78052 (b) (4)
-Nicole Allen, Director of Open Education for SPARC
In July 2018, a large-scale study was published that examined the impact of OER on student success metrics. The study evaluated the academic performance of 22,137 students in nine different courses at the University of Georgia. Each of these courses was taught by a professor who switched from a commercial textbook costing $100 or more to a free, open textbook from OpenStax.