Many existing Computer Assisted Learning (GAL) systems use computer programs to simulate a teacher for individual learning. However, regardless of how good the CAL system is, a student should also interact with learning companions and human teachers. Due to the popularity and ease of access to computer networks and communication tools, network facilities can be incorporated into a CAL system to make it a distance CAL system. To attain an effective learning outcome, a distance CAL system must be able to: define a group learning model; constrain and advise the students to learn according to the model, and have query facilities which provide the teacher with information about what a student has done and learned, and what a student should do next. A rule-based system that is conventionally used cannot sufficiently provide those required functions. This paper suggests why this is the case and how an active database system can achieve those goals.
