The framework is used currently by our group as a basis for design and re-design of several ILE and authoring tools. We think that our experience demonstrate one of the most reliable and natural ways of developing ITS authoring tools. First step is designing a number of ILE based on the same conceptual approach. It lets the designers to understand what part of the overall work is the same for different systems. That allows a research team to form a kind of a toolkit for internal use which facilitates the design of new systems.
Third step implies the development of some authoring support tools to be used with the toolkit.
And it is the way our group is going. In this paper we are trying to analyze and generalize our experience. Then we present our approach in a generalized form and discuss its application for authoring. The overlay student model reflects the extent to which the student has mastered language concepts by providing an integer weight for each concept. All learning material is also related with the domain model network.