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Modeling students’ knowledge is a fundamental part of intelligent tutoring systems. One of the most popular methods for estimating students’ knowledge is Corbett and Anderson’s [6] Bayesian Knowledge Tracing model. The model uses four parameters per skill, fit using student performance data, to relate performance to learning. Beck [1] showed that existing methods for determining these parameters are prone to the Identifiability Problem: the same performance data can be fit equally well by different parameters, with different implications on system behavior. Beck offered a solution based on Dirichlet Priors [1], but, we show this solution is vulnerable to a different problem, Model Degeneracy, where parameter values violate the model’s conceptual meaning (such as a student being more likely to get a correct answer if he/she does not know a skill than if he/she does).We offer a new method for instantiating …