The best line in this article is from another article wherein it is stated that "even if there is a learning benefit of [increasing access to] OER, standard research methods are unlikely to detect it." Which tells us a lot about both open educational resources (OER) and research methods. This is a good post, but as usual, I have my quibbles. For example, making a resource 'open' is not the same as changing the copyright. Openness isn't licensing; if it were, there would be no commercial open educational resources. And while it's true that you learn by doing, and not merely consuming, it seems wrong to talk about the 'instructional design' of a book (as opposed to, say, the content of a book). But yeah, "it matters far less which materials students are using than what students are doing with them." Or anybody (not just students).