Simulated Student: Building Cognitive Model by Demonstration

Noboru Matsuda

School of Computer Science

Carnegie Mellon University

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CTAT

• Works great for the Example-Tracing Tutors

– A cognitive model specific to a particular problem

• For Model-Tracing Tutors, the author must build a generalized cognitive model from scratch

– Writing production rules is challenging

– Also need a cognitive task analysis

– Performing a task is much easier…

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Simulated Students

• Machine learning agent that …

– Observe model solutions

– Learn problem-solving steps

– Outputs a set of production rules

• Model of human students learning cognitive skills

• Programming by Demonstration

Lau, T. A., & Weld, D. S. (1998). Programming by demonstration

Blessing, S. B. (1997). A programming by demonstration authoring tool for model-tracing tutors

}Both for correct and incorrect steps

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Next Generation AuthoringBuild a tutor GUI

Demonstrate a solution

SimSt. learning

Rule simplify-LHS:

IF is-equation( Eq ),

is-lhs( Eq, Lhs ),

polynomial( Lhs ),

all-var-terms( Lhs )

Then simplify( Lhs, S-lhs ),

enter( S-lhs )

Production Rules

Rule simplify-LHS:

IF is-equation( Eq ),

is-lhs( Eq, Lhs ),

polynomial( Lhs ),

all-var-terms( Lhs )

Then simplify( Lhs, S-lhs ),

enter( S-lhs )

Rule simplify-LHS:

IF is-equation( Eq ),

is-lhs( Eq, Lhs ),

polynomial( Lhs ),

all-var-terms( Lhs )

Then simplify( Lhs, S-lhs ),

enter( S-lhs )

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No Free Lunch

• Background knowledge– Operators

– Feature predicates

• External Jess function written in Java

(defrule multi-lhs…?var22140 <- (column (cells ? ? ?var22143 ? ? ? ? ?))?var22143 <- (cell (value ?val0&~nil))

(test (fraction-term ?val0 )) =>

(bind ?val2 (denominator ?val0))(bind ?input (mul-term-by ?val0 ?val2))…

)

7 PSLC Summer Intern Seminar :: Noboru Matsuda :: July 11, 2006PSLC Summer Intern Seminar :: Noboru Matsuda :: July 11, 2006

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Example: Stoichiometry Tutor

Approximate Time Distribution (hours)

55

30

15

40

Operator generation

Feature predicate generation

Debugging

Testing

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Learn more about Simulated Students

http://www.cs.cmu.edu/~mazda/CTAT/SimSt/

Example Tutor (Equation)

User’s Guide

… and more would come soon

Send email to mazda@cs.cmu.edu (Noboru)