Boudreaux Shaffer Heron McDermott - AJP 2008

Student understanding of control of variables: Deciding whether or not a variable influences the behavior of a system
Andrew Boudreaux
Department of Physics and Astronomy, Western Washington University, Bellingham, Washington 98225
Peter S. Shaffer, Paula R. L. Heron, and Lillian C. McDermott
Department of Physics, University of Washington, Seattle, Washington 98195
(Received 15 June 2007; accepted 13 October 2007)

The ability of adult students to reason on the basis of the control of variables was the subject of an extended investigation. This paper describes the part of the study that focused on the reasoning required to decide whether or not a given variable influences the behavior of a system. The participants were undergraduates taking introductory Physics and K–8 teachers studying physics and physical science in inservice institutes and workshops. Although most of the students recognized the need to control variables, many had significant difficulty with the underlying reasoning. The results indicate serious shortcomings in the preparation of future scientists and in the education of a scientifically literate citizenry. There are also strong implications for the professional development of teachers, many of whom are expected to teach control of variables to young students.

©2008 American Association of Physics Teachers

PACS: 01.40.Fk