Proceedings of the Annual Meeting of the Cognitive Science Society

The ACT Programming Tutor provides assistance to students as they write short computer programs. The tutor is constructed around a set of several hundred programming rules that allows the tutor to solve exercises step-by-step along with the student. This p^)er evaluates the Oitor's student modeling jx^ocedure that is used to guide remediation. This procedure, termed knowledge tracing, employs an overlay of the tutor's programming rules. In knowledge tracing, the tutor maintains an estimate of the probability that the student has learned each of the rules. The probability for a rule is updated at each opportunity to apply the rule, based on the student's performance. The predictive validity of the modeling procedure for tutw performance accuracy and posttest performance accuracy is assessed. Individual differences in learning parameters and cognitive rules are discussed, along with possible improvements in the modeling procedure.