Mobile devices are becoming more and more important in the context of e-learning. This requires appropriate models for structuring and delivering content to be used on various devices. Different technical characteristics of devices as well as different needs of learners require specific approaches. In this paper we propose a model for structuring content that allows rendering for different devices like Notebooks, PDAs, and Smartphones as well as presentation of the content in different levels of details according to didactic concepts like case study, definition, example, interaction, motivation, directive. This approach allows adaptation of content (device, granularity of content, content selection based on didactic concepts) at run time to specific needs in a particular learning situation. The approach realized in the joint MobiLearn project of several universities in Austria shows high acceptance by students during an initial pilot application.