Learning about atoms, molecules, and chemical bonds: A case study of multiple-model use in grade 11 chemistry

Analogical models are frequently used to explain science concepts at all le vels of science teaching and learning. But models are more than communicati ve tools: they are important links in the methods and products of science. Different analogical models are regularly used to teach science in secondar y schools even though little is known about how each student's mental model s interact with the various models presented by teachers and in textbooks. Mounting evidence suggests that students do not interpret scientific analog ical models in the way intended, nor do they find multiple and competing mo dels easy to understand. The aim of this study is summarized in the researc h question: How can students' understanding of the multiple models used to explain upper secondary chemistry concepts be enhanced? This study qualitat ively tracked ten students' modeling experiences, intellectual development, and conceptual status throughout grade 11 as they learned about atoms, mol ecules, and chemical bands. This article reports in detail a year-long case study. The outcomes suggest that students who socially negotiated the shar ed and unshared attributes of common analogical models for atoms, molecules , and chemical bonds, used these models more consistently in their explanat ions. Also, students who were encouraged to use multiple particle models di splayed more scientific understandings of particles and their interactions than did students who concentrated on a "correct" or best analogical model. The results suggest that, when analogical models are presented in a system atic way and capable students are given ample opportunity to explore model meaning and use, their understanding of abstract concepts is enhanced. (C) 2000 John Wiley & Sons. Inc.