Using the Student Model to Control Problem Difficulty

We have created a student model which dynamically collects information about a student,s problem solving ability, acquisition of new topics and retention of earlier topics. This information is provided to the tutor and used to generate new problems at the appropriate level of difficulty and to provide customized hints and help. Formative evaluation of the tutor with 20 students provides evidence that the student model constructs problems at the correct level of difficulty. The problem generation technique is extensible for use in other problembased domains. This paper describes the design and implementation of the student model and illustrates how the tutor adjusts the difficulty of a problem based on the student model.