Using modeling languages is essential to the construction of educational systems based on software engineering principles and methods. Furthermore, the instructional design is undoubtedly the cornerstone of the design and development of educational systems. Although several methodologies and languages have been proposed for the specification of isolated educational multimedia systems, none has optimum results for the description of these systems and, especially, for their pedagogical aspect. Of course this is due primarily to how these systems function and are applied; it is not due to the language itself, although its special characteristics contribute substantially to the development of these systems sometimes positively and sometimes negatively. In this paper, we briefly describe the introduction of stereotypes to the pedagogical design of educational systems and appropriate modifications of the existing package diagrams of UML (Unified Modeling Language). The main objective of these new stereotypes is to describe sufficiently the mechanisms of generation, monitoring and re-adapting of teaching and student's models which can be used in the educational applications. (Contains 4 figures and 4 tables.)