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  Home > JCE Print > Journal of Chemical Education > Issues > 2005  > August  >
In the Classroom
Cross-Proportions: A Conceptual Method for Developing Quantitative Problem-Solving Skills
Elzbieta Cook and Robert L. Cook
Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803 and Department of Chemistry, Southern University and A&M College, Baton Rouge, LA 70813
Cover
August 2005
Vol. 82 No. 8
p. 1187
Abstract
This paper focuses attention on the cross-proportion (C-P) method of mathematical problem solving, which was once widely used in chemical calculations. We propose that this method regain currency as an alternative to the dimensional analysis (DA) method, particularly in lower-level chemistry courses. In recent years, the DA method has emerged as the only problem solving mechanism offered to high-school and general chemistry students in contemporary textbooks, replacing more conceptual methods, C-P included. The C-P method emphasizes basic scientific principles through application during the process of solving numerical problems, which in turn promotes student understanding of these principles by constantly reinforcing basic concepts. We believe that appropriate teaching of chemistry needs to model its conceptual character as well as address students' different learning styles. Examples of C-P applications to molar mass and stoichiometry are given.
Supplement
Several additional examples from general chemistry are available.
*  Contents JCE2005p1187W.doc (Microsoft Word)
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*  Citation
 Cook, Elzbieta; Cook, Robert L. J. Chem. Educ. 2005 82 1187.
*  Keywords
 Chemical Education Research; Learning Theories; Problem Solving / Decision Making; Stoichiometry; Student-Centered Learning
*  History
 Created:
Last Updated:		 July 5, 2005
August 24, 2005
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