Evaluating OERs is not very different from evaluating any other sort of text or learning material, but there are a few additional criteria to take into account when deciding whether or not an OER is appropriate for your purposes. Many OERs are not published by traditional publishers, and some of these may require a bit of additional scrutiny to determine their quality. One aspect of open textbooks that varies greatly from traditional textbooks is the open licensing aspect which allows the material to be modified as the professor sees fit. See the open licensing tab for more information on this. In order to use the material in the way that you want, you need to make sure that the license on it permits the use you have in mind. Another way in which open textbooks are different from traditional textbooks is that they are almost always "born digital," meaning that the text exists only in a digital format. It is important to consider how your students will want to access the material to see if an open textbook will be right for you.