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Demonstrating chemistry phenomena and stimulating back-and-forth thinking of students between phenomena, concepts, and various representations and visualizations

T. C. Visser, L.A. de Graaf, E van den Berg, W.P. Spaan

 

Abstract

Johnstone’s “chemistry triangle” comprises three levels of processing to describe and explain chemical phenomena: Macro-, Micro-, and Symbolic-level. Experienced chemists can easily switch between the different levels, but learners often struggle to do so. Students have to learn to think back-and-forth between phenomena and theory and switch between the three levels of description and explanation of phenomena. This article describes the relationship between hands-on and minds-on approaches to learning chemistry concepts through teacher demonstrations. We provide guidance and a strategy to facilitate smooth switching between the different levels. In Section 1 we introduce “meaning-making” through Thinking Back-and-Forth (TBF) between the Domain of Observables (phenomena, objects, and observations) and the Domain of Ideas (concepts, theories, and models). In Section 2, the back-and-forth thinking model is expanded to incorporate the various levels of processing as outlined in Johnstone’s “Chemistry Triangle”. Finally, in Section 3, we conclude with some strategies for visualizing the micro level. To illustrate the back-and-forth thinking between phenomena, concepts, and visualizations we used the example of the reaction between a copper(II)nitrate solution and iron nail/ steel wool.