As is the case with most of science education, instruction in organic chemistry heavily relies on the use of multiple external representations (MERs), including verbal/linguistic and a diverse array of diagrammatic forms. MERs can be a particularly powerful tool since they can offer students a variety of perspectives from which to view and learn concepts and theories. However, this potential assumes that students have a minimal fluency in multiple representational forms and formalisms. As part of our ongoing interest in mechanistic reasoning using the electron-pushing formalism, we are investigating how students transfer between verbal/linguistic and diagrammatic representations of electron-pushing mechanisms. Preliminary data from a qualitative study of second-semester students in the sophomore-level organic chemistry sequence (Organic Chemistry II) indicate that they have significant difficulty in verbally describing electron-pushing diagrams or producing them from verbal descriptions of electron-pushing mechanisms.Subsequently, we performed an empirical study to test the hypothesis that verbal/linguistic descriptions do not help students understand reaction mechanisms. Organic Chemistry II students were randomly assigned to one of three conditions in which they were given: verbal description of a mechanism only; diagram of a mechanism only; verbal description and diagram. After a learning phase with their respective materials, students were asked to complete a set of electron-pushing tasks in which starting material, reagents, and products were provided. The independent variable was the format of the learning material and dependent variable was the score on the mechanism tasks, which was obtained from ratings by multiple individuals. Analysis of covariance (ANCOVA) was performed on a linear regression model that included prior knowledge and overall GPA as covariates. In addition to presenting the results of this work, I will discuss their implications for instruction and future investigations.

Multiple external representations: Synergy or interference?

247th National Meeting (2014)

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