Learning object (LO) and Educational Modelling Language (EML) refer to two of major trends in the field of elearning engineering. The former consists, on the one hand, in reusing as well as possible existing resources when we are creating a new elearning situation and, on the other hand, in indexing new resources to facilitate their dissemination and reuse. The latter consists in using an EML to describe elearning situations and then create a framework of LO’s aggregation. Such a language allows producing instructional scenarios. Although numerous works are about LO and EML, few of them concerned the validation of instructional scenarios. In this paper, we introduce these works and present a new technique of scenario validation driven by the competencies which are associated with the scenario and its components (notably LO). We believe our solution is useful to aim to production of high quality online learning. Semantic Web technologies and ontological engineering are used to develop an assistant tool to scenario production (LEO).