Abstract
In this paper, we discuss an intelligent educational system for high-school chemistry that helps learners who do not understand structures of chemical substances. In order to help such learners, it is not enough to merely display the relevant structures. We propose a method taking advantage of virtual phenomena representing how the substances are composed. In order to deal with virtual phenomena, we improve our prototype system by extending the chemical reaction simulator and the problem solver for exercises. We also illustrate implementation of our extended system and the experimental evaluation of it.