Andrew Boudreaux
Department of Physics and Astronomy
Western Washington University

Title: 
Examining how students reason with multiple variables

Abstract:
In many topics in introductory physics, students must reason about situations 
that involve multiple variables.  For example, when analyzing an ideal gas system, 
students are taught that the pressure of a gas is inversely proportional to its 
volume, given a constant temperature and number of moles. When considering the 
flow of an ideal fluid through a pipe, students must recognize that changes in 
elevation and pipe diameter contribute independently to the pressure difference 
between two points. At Western Washington University, we are examining students’ 
multi-variable reasoning in a variety of contexts.  In some cases, students seem 
to focus inappropriately on a relationship between two variables, without attending 
to the experimental conditions under which that relationship has been established.
In other situations, students have difficulty recognizing situations in which the 
competing effects of two different variables render a qualitative analysis incapable 
of predicting the behavior of the system.  In this talk, student responses on written 
assessment tasks will be used to illustrate specific difficulties.