The research presented in this paper takes as its starting point a review of the knowledge modeling capabilities of Educational Modeling Languages (EMLs)and in particular of the EML-OU from the Open University of the Netherlands. We explain how educational designers need modeling languages addressing cognitive, structural and social aspects of education. For each of these three aspects, we make proposals which some might consider as extensions of the EML-OU language. However, we choose to incorporate these extensions within a UML profile at a meta-level of EML-OU