Evaluating Open Educational Resources is the same process as evaluating traditional textbooks. Here is a list of rubrics and resources that can help you evaluate OER you are considering using:
Achieve's 8 detailed OER rubrics
A rubric developed by Sarah Morehouse with help from Mark McBride, Kathleen Stone, and Beth Burns that provides some great questions to ask when evaluating OER.
Affordable Learning Georgia's OER Evaluation Criteria
Evaluating Open Educational Resources (OER) - Zahnow Library
This is a sample rubric to assist you in deciding the suitability of an OER, created by the Scholarly Communications Librarian at Zahnow Library.