Open Educational Resources (OER): are freely accessible, openly licensed text, media, and other digital assets. These resources can be used for teaching, learning, and assessing as well as for research purposes.
Many states, school districts, colleges, and universities are going to Open Educational Resources as a way to customize curriculum, provide information from a variety of sources and in multiple formats, meet the different need of their students, and of course, save money by using digital content.
For more information on the #GoOpen campaign visit the Department of Education website: https://tech.ed.gov/open/
Donya Gartside
West Middle School
Lincoln
Liberty
Garfield
Union
Other OER collections
National Science Digital Library
OpenStax, a service offered by Rice University, offers access to high-quality textbooks for both K-12 and university students. This project was initially kicked off for college students by the Bill and Melinda Gates Foundation.
https://openstax.org
Curriki isn't just about free textbooks, although you can find those at the site. Curriki offers a fantastic array of free educational resources, anything from science kits to novel studies.
http://www.curriki.org
Project Gutenberg offers a wide selection of over 50,000 texts at the time of this writing, with more available through their partner websites. Browse through their categories, search for something specific, or take a look at their entire catalog.
http://www.gutenberg.org
OER Commons
https://www.oercommons.org
The Community College Consortium for Open Educational Resources is simply laid out, giving users the ability to search within selected subject areas for free textbooks.
http://www.oerconsortium.org/discipline-specific
Bookboon offers a wide variety of free textbooks here; you will need to give your email address to this site in order to download anything, and will receive a weekly update of new books and additions to the site. Premium access is also available for a fee.
http://bookboon.com
From the California Learning Resource Network, the Free Digital Textbook Initiative offers a good selection of free content materials suitable for both high school and college students.
https://www.oercommons.org/browse?f.keyword=california-free-digital-textbook-initiative
Wikibooks
Wikibooks offers a wide variety of free textbooks (more than 2,000 the last time we looked), in subjects from computing to social sciences.
https://en.wikibooks.org/wiki/Main_Page
Georgia Tech Math books
Professors from the Georgia Institute of Technology have collated an impressive list of online mathematics texts, ranging from calculus to mathematical biology.
http://people.math.gatech.edu/~cain/textbooks/onlinebooks.html
Textbook Revolution
Run by students, Textbook Revolution offers free books organized by subject, license, course, collections, topic, and level. Easily searchable with a healthy amount of subject matter available.
http://www.textbookrevolution.org/index.php/Main_Page
MIT has offered free, open courseware for several years now, and along with these free classes comes free college textbooks. You'll have to search for specific classes and/or titles of books on the site in order to find what you're looking for; overall, there is a lot of free content available here in a wide variety of subjects
https://ocw.mit.edu/index.htm