A major benefit of choosing an open educational resource is that it gives faculty the legal right to add to, adapt, or delete content from the open work to fit their specific course without obtaining permission from the copyright holder.
Check the license of the work - does it allow for modifications or derivatives?
Check the format of the work - common formats are HTML files (webpages), Word or open documents (Google Docs), Text files, ePub, LaTex files (if the original book includes math or science formulas and equations).
Choose tools for editing an open textbook (or other open resource) - there are many available. Choosing an editing tool may depend on the original format of the resource.
Choose the output for the work - students like having material in multiple formats. This allows them to choose what works best for them. Some may prefer printed versions of the textbook; others will prefer using a website. Still others will like to use an e-reader or e-reading software. By offering multiple formats you are making your content more accessible.
Determine access for the work - how will students access the content? Will it be available in an LMS, Google Classroom, OER Commons, or another online hosting service?
Choose a license - the open license chosen will depend on both the author’s/creator’s preferred permissions, and how the original resource was licensed. For example, if the original resource was licensed with a Creative Commons Attribution-ShareAlike (CC BY-SA) license, then the revised resource must be published with the same license to ensure it is compliant with the terms of use.
Remember only works that align with the 5Rs are considered Open Educational Resources.
For a complete guide to adapting OER Textbooks, see Modifying an Open Textbook: What You Need to Know, from the Rebus Community.