Resumen de Compromised Structures: Verbal Descriptions of Mechanism Diagrams
Gautam Bhattacharyya, Michael S. Harris
We report our research of seven pairs of students enrolled in the second semester of sophomore-level organic chemistry as they attempted to describe (in their own words) and draw, respectively, three electron-pushing diagrams of three-step reaction mechanisms. The tasks’ objective was to accurately reproduce the diagrams based solely on the mechanistic language descriptions, because the goals of this research were to identify characteristics of effective descriptions and to describe factors that impede students in constructing those descriptions. Both members of each pair had at least one opportunity to describe and one to draw. To eliminate nonverbal communication the students were unable to see each other but were free to ask questions to their partners. Though most of the groups were able to successfully replicate the diagrams, they struggled to describe and draw chemical structures. Instead of falling back on the IUPAC system of nomenclature, they used iconic symbols and geometric shapes to characterize the structures. The participants were able to communicate the positioning of the curved arrows of the electron-pushing formalism with relative ease. The main instructional implications are that students need (1) intensive help with constructing and using Lewis structures and (2) scaffolding with explanations that gradually transition from explicit aspects of diagrams to the implicit, deeper ones.
