OER can led to using unverified materials by teachers and students
The level of assurance you can get from OER materials can be the same as with traditional materials: high when from institutionally reviewed process, lower when not reviewed or just found on the web. It depends on the country, but most of teachers are allowed to use own materials and textbooks. They are also using their reasonable judgment before using any learning resources (even many reviewed and edited textbooks have errors). Teachers use materials found on the web, not reviewed, peer produced by other teachers, often being not attributed (and infringing to copyright owners) adaptations of textbooks and other resources. The truth is that the quality of “OER depends on which resources they choose to use, how they choose to adapt them to make them contextually relevant, and how they integrate them into teaching and learning activities of different kinds” (COL, UNESCO, 2011).
OER and open licensing model introduced strong approach to respect the rights of authors and to support effective online sharing of open materials. Modified OER (and any openly licensed material) have to be attributed properly and described with changes and reference to original material. Of course there will be situations when this will not happen but this does not differ from any authorized edited copy of other, closed materials we can find on the web right now. For those circumstances in which absolute assurance is required teachers and students can choose to use materials for which they can get additional assurances for example: provided by specific specialized repositories, reviewed and certified, etc.
Want to know more?
Basic Guide to Open Educational Resources, Commonwealth of Learning, UNESCO, 2011, p. 12, Who will guarantee the quality of OER?