A New Paradigm for Intelligent Tutoring Systems: Example-Tracing Tutors

In IJAIED 19 (2): "Authoring Intelligent Tutoring Systems"

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The Cognitive Tutor Authoring Tools (CTAT) support creation of a novel type of tutors called example-tracing tutors. Unlike other types of ITSs (e.g., model-tracing tutors, constraint-based tutors), example-tracing tutors evaluate student behavior by flexibly comparing it against generalized examples of problem-solving behavior. Example-tracing tutors are capable of sophisticated tutoring behaviors; they provide step-by-step guidance on complex problems while recognizing multiple student strategies and (where needed) maintaining multiple interpretations of student behavior. They therefore go well beyond VanLehn’s (2006) minimum criterion for ITS status, namely, that the system has an inner loop (i.e., provides within-problem guidance, not just end-of-problem feedback). Using CTAT, example-tracing tutors can be created without programming. An author creates a tutor interface through drag-and-drop techniques, and then demonstrates the problem-solving behaviors to be tutored. These behaviors are recorded in a “behavior graph,” which can be easily edited and generalized. Compared to other approaches to programming by demonstration for ITS development, CTAT implements a simpler method (no machine learning is used) that is currently more pragmatic and proven for widespread, real-world use by non-programmers. Development time estimates from a large number of real-world ITS projects that have used CTAT suggest that example-tracing tutors reduce development cost by a factor of 4 to 8, compared to “historical” estimates of ITS development time and cost. The main contributions of the work are a novel ITS technology, based on the use of generalized behavioral examples to guide students in problem-solving exercises, as well as a suite of mature and robust tools for efficiently building real-world ITSs without programming.