Guided Perspective Drawing: A Model-Based Method to Build Representational Competence in Organic Chemistry

Many approaches to teaching Newman projections and conformational manipulation rely on lecturing using only two-dimensional representations. While molecular models are recognized as useful learning tools, students are often left to figure out how to use them during the initial learning process. The availability of basic online molecular models provides additional opportunity for practice, but having three different learning modalities (drawings, hand-held models and computer models) creates the need for a systematic teaching approach that integrates these. A model-first teaching method is presented in which Newman projections and the conformations of butane are taught through a guided exercise in drawing molecular models in specific conformations from two viewpoints. The viewpoints correspond to the Newman projection and the bond line drawing, linking them to each other through the 3D object that they both represent. Participation in this exercise correlated with significantly higher competency in translating between the two representations compared to a large control group, who attended the lecture but did not use the models. This method was then extended into a multimodal peer-to-peer learning activity where students applied these skills by critically evaluating differences in conformational or stereochemical details between a 2D molecular drawing prompt and a computer-generated 3D model. Students were able to rotate the computer model to find the point of view corresponding to Newman projections or bond-line drawings, use hand-held models to analyze the differences, and discover stereochemical insights that had not yet been taught.