To meet the needs for large-scale, high-quality learning contents, needless to say, we have to sharpen authoring tools. Authoring process can be roughly divided into two phases, a composing phase and a verification phase. A great deal of effort has been made on the support in the former phase. What seems to be lacking, however, is that in the latter. An ontology-aware authoring tool we have been developing has a function called “Conceptual level simulation.” This supports authors in the latter phase by showing the behavior of learning contents not only as a sequence of concrete behavior but also as structured and abstract behavior along the design intention. Ontology lays the foundation for the function by explicating operational and conceptual semantics of a training scenario.