Intelligent Computer tutoring Group (ICTG) has developed several constraint-based tutors. We adopted and enhanced Constraint-Based Modeling (CBM), a student modeling approach proposed by Ohlsson (1994). In this interactive demo, we will present our three database tutors, which have also been commercialized on the Addison-Wesley’s DatabasePlace Web portal (http://www.awbc. com/databaseplace/). All our ITSs are Web-enabled, and their typical architecture is shown in Figure 1. The session manager is responsible for taking care of student sessions, and logging their actions. The student communicates with the ITS through an interface served in a Web browser. Student models are generated and maintained by a student modeller. The student’s solution is diagnosed by matching it to the constraints describing the domain principles. The pedagogical module determines the timing and content of pedagogical actions. The optional components involve the problem solver, the group modeller and modules supporting open student models and metacognitive skills. We have performed more than 30 studies in real classrooms since 1998. Our database tutors have proved to be very effective in supporting deep learning, and are well liked by students.