Elaborating Models of Algebraic Expression-Writing

This paper discusses the refinement of the algebraic expression-writing rules for the PAT Algebra I tutor, between 1992 and 1997. Direct observation of students in class, step-by-step PAT tutor protocols tracing student behavior, and statistical analysis of protocol data, have all informed our understanding of students' skills, and our refinement of this part of PAT's production model.