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CMU-CS-01-127
Computer Science Department
School of Computer Science, Carnegie Mellon University
CMU-CS-01-127
Intelligent Tutoring Systems have Forgotten the Tutor:
Adding a Cognitive Model of Human Tutors
Neil T. Heffernan III
March 2001
Ph.D. Thesis
CMU-CS-01-127.ps
CMU-CS-01-127.pdf
Keywords: Model-tracing, cognitive model, intelligent
tutoring system, artificial intelligence, tutoring, mathematical
education
This dissertation makes a contribution to 1) the cognitive science of
algebra learning as well as to 2) intelligent tutoring systems
architectures. I present a new intelligent tutoring system for the
domain of writing expressions for algebra "story" problems. This
system is novel, because it is the first intelligent algebra tutor
that combines a cognitive model of the domain with a rich pedagogical
model of dialog-based tutoring. The algebra model is novel because
contrary to prior work that has emphasized the difficulties of using
variables, as well as the difficulties of comprehending the text of a
word problem, I establish the empirical result that articulating a
complete expression (e.g., 800-40*3) is a major determinant of
problem difficulty. The tutorial model is also novel because it is
based on the observation of an experienced human tutor and captures
the rich tutorial strategies specific to the domain of symbolization.
The resulting system, called Ms. Lindquist, has been demonstrated to
improve student learning. Over 350 students have used the system
available at www.AlgebraTutor.org.
187 pages
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