Inferring the Context for Evaluating Physics Algebraic Equations When the Scaffolding Is Removed

C. W. Liew, Joel A. Shapiro, and D. E. Smith

This paper describes our continuing work on enabling a tutor to evaluate algebraic solutions to word problems in physics. Current tutoring systems require students to explicitly define each variable that is used in the algebraic equations. We have developed a constraint propagation based heuristic algorithm that finds the possible dimensions and physics concepts for each variable. In earlier work we developed techniques that worked for a small set of problems and evaluated them on a small number of students. The work described here covers an extension to and evaluation of a much larger class of problems and a larger number of students. The results show that our technique uniquely determines the dimensions of all the variables in 89% of the sets of equations. By asking the student for dimension information about one variable, an additional 3% of the sets can be determined. Thus a physics tutoring system can use this technique to reason about a student’s answers even when the scaffolding and context are removed.

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