Patterns of reactions: a card sort task to investigate students’ organization of organic chemistry reactions

Research has shown that within a traditional organic chemistry curriculum, organic chemistry students struggle to develop deep conceptual understanding of reactions and attribute little meaning to the electron-pushing formalism. At the University of Ottawa, a new curriculum was developed for organic chemistry in which students are taught the language of the electron-pushing formalism prior to learning about specific reactions. Reactions are then organized by governing pattern of mechanism rather than by functional group and are taught in a gradient of complexity. To investigate how students are making connections across reactions within the new curriculum, a card sort task was developed. The card sort task consisted of 25 cards, each depicting the reactants and solvent for a reaction taught during the two-semester organic chemistry sequence. The first part of the task asked participants to sort 15 of 25 cards into categories. Then, participants were given the 10 remaining cards to incorporate into categories with the previous 15. Participants were asked to explain the characteristics of each category and their sorting process. Students (N = 16) in an organic chemistry course were interviewed while enrolled in the second semester course. We analyzed the students’ sorts based on which cards were sorted frequently together, the underlying characteristics used to form the categories, and the participants’ sorting processes. Participants created categories based on different levels of interpreting the reactions on the cards, with levels ranging from recognizing identical structural features to identifying similar types of mechanisms. Based on this study, if we want students to develop mechanistic thinking, we think students need to be more explicitly directed to the patterns present in organic reaction mechanisms and given opportunities to uncover and identify patterns on their own, during both summative and formative assessments.