In all learning scenarios and especially mobile and collaborative ones, the learner?s context is an essential asset in designing the learning process. Researches in context aware mobile learning have concentrated on how to adapt applications to context. In this paper, we present an innovative approach for modeling a bijective adaptation between context and learning activities because they influence each others in learning processes. Furthermore, it proposes an ubiquitous middleware, a new multi-layer conceptual framework for building contextaware mobile learning systems. This framework supports tasks including: acquiring, interpreting, modeling, storing, reasoning, updating and adapting context. The originality of this framework comes especially from its top-most layer which is an adaptor that defines two classes of functionalities: the adaptation of learning activity to context and the adaptation of context to learning activity.