The terms “open content” and “open educational resources” (OERs) describe any copyrightable work (traditionally excluding software, which is described by other terms like “open source”) that is either (1) in the public domain or (2) licensed in a manner that provides everyone with free and perpetual permission”* In many cases, OERs can supplement or replace proprietary textbooks altogether without sacrificing quality. Using OERs saves students hundreds of dollar each semester and can be accessed immediately without shipping delays, a ‘win win’ scenario for teachers and students!
This spreadsheet lists open educational resources (OERs) by broad (and sometimes overlapping) groups: open access textbooks, search engines of open access teaching content, open access courses (i.e. an entire courses that can be taken online at anytime), and library resources (not open access, per se, but still permissible for educational use). You can click on the tabs at the bottom to find suggestions for each course in that discipline or download the spreadsheet.
*This definition was copied verbatim from: Defining the “Open” in Open Content and Open Educational Resources was written by David Wiley and published freely under a Creative Commons Attribution 4.0 license at http://opencontent.org/definition/. Read more about OERs here.