Mechanisms, Models, and Explanations: Analyzing the Mechanistic Paths Students Take to Reach a Product for Familiar and Unfamiliar Organic Reactions

• Samantha K. Houchlei ^[1] ; Rosalyn R. Bloch ^[1] ; Melanie M. Cooper ^[1]
  1. [1] Michigan State University

     Michigan State University

     City of East Lansing, Estados Unidos

     
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 98, Nº 9, 2021, págs. 2751-2764
• Idioma: inglés
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• Resumen

  • This study is a follow up to two earlier studies characterizing student real-time use of mechanistic arrows. In these previous studies, students were asked to predict a product by drawing a curved arrow mechanism using an interface that allowed recording and replay of student actions. In the present study two different student cohorts responded to the same tasks as the original studies: a cohort who were enrolled in a traditional organic course, and a cohort who were part of a transformed organic course (Organic Chemistry, Life, the Universe and Everything, OCLUE). Both cohorts improved in their ability to predict an appropriate product over the two semesters, and we found little meaningful difference in the ability of students from either cohort to predict the outcome of a familiar reaction. However, students in the OCLUE cohort were more likely to draw mechanistic arrows than the students from the traditional course. In contrast, when the task involved predicting the product of an unfamiliar reaction, OCLUE students were over three times more likely to draw mechanistically reasonable steps and produce a plausible product than students from the traditional cohort. We propose that the differences between the two cohorts emerge from the following: (1) explicit attempts in the OCLUE course to link drawing reactions mechanisms using the electron pushing formalism to the scientific practice of constructing explanations. It is our contention that this approach changes the arrow pushing mechanism from a skill to the construction of a model which students can use to predict and explain outcomes; and (2) the numerous opportunities in the OCLUE course to try out ideas without penalty, leading to a willingness to try to determine outcomes in unfamiliar situations.