OER are too complex and scattered for teachers to use
In most circumstances and for more teachers, who are already ICT qualified, the level of assurance you get from OER materials is enough. Most of the teachers and students use resources found on the Internet, often without any consideration about rights and authority of authors. For all resources, and among those available on the internet we should use reasonable judgment. OER are based on a clear copyright and creation process information about what rights apply to such resource, is it original or is it a transformation of other work. Such culture is safer and more reliable but it needs some competencies from teachers (and students as well). That is why it is often said that OER are also part of media literacy and copyright education.
In case of using open textbooks complexity starts when we want to re-use such materials and if textbook was created orderly all copyrights should be cleared and acknowledged.
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Prepping for the Geography Textbook Sprint, Clint Lalonde