HRK HochschulrektorenkonferenzOpen Education Resources (OER) are freely available teaching materials which can be used, revised, recompiled and distributed by all participants. However, their usage can be limited with a system of graduated licences[1]. The fundamental idea underlying OER is that once teaching materials have been produced, they need not be produced again by someone else, but may be reused. "Open" can refer to the availability of content and to its wider use. Although OER can in principle consist of analogue or digital material, they take a predominantly digital form because this is particularly suitable for bringing the opportunities offered by OER to bear[2]. Interactive exercises, explanatory videos and simulations are typical examples of OER. More...