The operationalization of learning scenarios on learning management systems (LMS) is more than a technology related question. Different research issues around instructional design are to be address ed in order to provide pedagogical expressiveness of the different elements within a learning scenario, while it respects sufficiently the structure to describe it. In this work, we examine existing pattern based approaches for learning design, and we provide a pattern's formalism for learning designs that enables their deployment automatically on the chosen LMS. We have adopted a methodology elaborated on the basis of a case study on which we have executed a process of learning scenario's operationalization. One of the results was to prove the usefulness of a pattern's formalism to design learning scenarios. We have considered the structural, constraints and content aspects of a learning scenario from both human and computational point of view. The formalis m described in this paper is part of a process based on ontologies and semantic web principles, offering a support for teachers designers to produce deployable learning scenarios without having to master the target platforms.