According to the Bureau of Labor Statistics, the average cost of a textbook has increased 125% since 2002. Many students pay for textbooks with student loans, thus increasing their debt load. The use of OER helps to defray costs for students.
Additionally, the ability to adapt the material gives professors more control over the materials they use in class, letting the textbook fit the course instead of the course fitting around the textbook.
OER have been put into use in schools large and small, public and private. Here you'll find collections of OER by type and source, as well as news about OER initiatives all over the U.S.
Bureau of Labor Statistics. (2017, June 16). College textbooks in U.S. city average, all urban consumers, not seasonally adjusted [dataset]. Retrieved from https://data.bls.gov/pdq/SurveyOutputServlet.
OER materials are either in the public domain or have been licensed for reuse and, sometimes, remixing and redistribution. Publishers of open coursework, including textbooks, are generally supported by academic institutions and philanthropic foundations, and those who write them do so with the express purpose of making the materials freely available for use by other professors and students. This way, not only is the material available for anyone who needs it, but it's also easier to continually update and improve the information available within.
These collections include textbooks in a range of disciplines, all available to read online and download for free under Creative Commons licenses.
Course materials, such as full courses, lectures, lecture notes, and syllabi, can be found in the broad collections listed here.
The open access publishing of academic monographs is spreading. This is particularly true of many titles that would otherwise be out of print, but there is also a growing number of those initially published open. While these texts cannot be modified, they can definitely be assigned to students as part of course readings, and are available to read online and/or download for free.