Boundless, the company that builds on existing open educational resources to provide free alternatives to traditionally costly college textbooks, has released 18 open textbooks under Creative Commons Attribution-ShareAlike (CC BY-SA), the same license used by Wikipedia. Schools, students and the general public are free to share and remix these textbooks under this license. The 18 textbooks cover timeless college subjects, such as accounting, biology, chemistry, sociology, and economics. Boundless reports that students at more than half of US colleges have used its resources, and that they expect its number of users to grow.

Boundless has an entire section explaining open educational resources (OER) and how they use them. However, you can easily see how it works for yourself by browsing one of their textbooks directly. For example, see their textbook on Biology. At the end of each chapter, sources are cited as a list of links where you can find the original material:

This chapter on Organismal Interactions references a Wikipedia article and several articles in The Encyclopedia of Earth. If you follow these links, you will find that the original articles are OER governed by the same CC BY-SA license.

From Boundless’ FAQ,

Is it really free? How does Boundless make money?

Absolutely. Boundless books are 100% free with no expiration dates like textbook rentals or buybacks at the bookstore. It starts with Open Educational Resources. In the future, Boundless will implement some awesome optional premium features on top of this free content to help students study faster and smarter.

As you can see in the screenshot above, Boundless is already rolling out some of those premium features, including flashcards, study guides, and quizzes. To access these features Boundless requires a free user account. The textbooks themselves are completely open, without registration required, and are accessible at boundless.com/textbooks/.

For further reading, we recommend Slate’s article entitled, “Never Pay Sticker Price for a Textbook Again – The open educational resources movement that’s terrifying publishers.” It does a fantastic job of placing the company’s aims in the context of the current publishing ecosystem.