Exploring Students’ Initial Interpretations of the Electron-Pushing Formalism Arrows
Creators: name: Huang, Denzel
Publisher: name: Université d'Ottawa / University of Ottawa
Year: 2022
Subjects: subject: Chemistry Education Research
subject: Organic Chemistry
subject: FOS: Chemical sciences
subject: Electron-Pushing Formalism
subject: Language of Mechanisms

description: Chemists use the electron-pushing formalism to rationalize, analyze, and explain how a chemical reaction occurs on an electronic level. The electron pushing formalism (EPF) is the curved arrows representing electron movement. Some research on undergraduate organic chemistry students’ understanding of the electron pushing formalism has presented evidence that some students do not find the electron-pushing formalism meaningful. Research at the University of Ottawa found that the EPF symbolism is meaningful to the participants because they interpret EPF arrows and use charges and mapping to problem-solve. At the University of Ottawa, the organic chemistry curriculum was changed in 2012 to have students learn and interpret reactions based on similar reactivity patterns. The goal of the redesign was to give students the tools to analyze, predict, and explain how reactions occur instead of memorizing. An initial section of the curriculum is dedicated to teaching the electron-pushing formalism before any reaction. An exam analysis was conducted to see the new curriculum's effect by looking at students' drawn structures and EPF arrows. Students demonstrated minimal errors when drawing the EPF arrows and scored higher on familiar and unfamiliar reactions following the new curriculum, which suggests students found the EPF arrows meaningful. The following think-aloud interview study better captured student interpretations of the EPF arrows to determine what features students found relevant and whether the students who could explain a conceptual understanding of the EPF arrows could express a deeper understanding. The think-aloud interviews found that students do place meaning into organic chemistry representations as students were thinking about how to draw the EPF arrows based on prior knowledge. The data from the two previous studies were collected near the end of the course when students had a significant amount of experience, while students’ initial interpretations of the EPF arrows are needed. The primary focus of this thesis is to understand how students initially interpret the electron-pushing formalism arrows and look further into previous findings, which include electron movement, bond-forming and breaking processes, mapping, charges, stepwise reasoning, and transplanting electrons. Twelve students were recruited from Organic Chemistry I and interviewed over three weeks after being taught the electron-pushing formalism. The interviews were conducted using a think-aloud procedure to capture students’ thoughts, and each interview lasted approximately 1 hour. The instrument consisted of six organic chemistry questions, specifically chosen, as students would not encounter them in the class and would have to interpret the representations. The transcripts were analyzed with respect to the previous studies' findings and compared among participants to explore students’ interpretations and use of the EPF arrows. The findings from this study suggest participants found the EPF arrows meaningful because participants interpreted the representations as electron-movement, bond-forming, and bond-breaking processes which contrasts some prior research that reported students do not find the EPF arrows meaningful (Bhattacharyya and Bodner, 2005; Graulich, 2015). Participants connected the EPF arrows to electron movement, bond-forming, and bond-breaking processes. Participants compared surface features to determine how to draw the EPF arrows. Participants’ visualization and how they approached the reactions differed. Participants’ visualizations of the organic chemistry reaction were divided between a stepwise or concerted visualization. Most participants approached the EPF arrows stepwise as a problem-solving tool as it was easier for them to understand. Participants correctly interpreted most bond-breaking EPF arrows, but some participants relocated the electron pair onto a different atom instead of forming a bond. Participants mainly mapped the carbon atoms with numeric labels and found implicit atom-type questions challenging. Participants interpreted charges as an important surface feature and used charges to help them solve the question. Participants viewed charges as a reactive location where bonds break and form and compared the number of charges between reactants and products to check whether their answers were correct. The results suggest the participants in the study found the EPF arrows and made meaningful connections at the submicroscopic level with minimal experience. Mastering the EPF arrows at the beginning of the course appears beneficial to student learning because participants interpreted the EPF arrows as a meaningful representation suggesting that the EPF arrows are less of a barrier when learning and mastering organic chemistry, under the University Of Ottawa’s organic chemistry curriculum as intended. Since the EPF arrows are less of a barrier, students can focus on other organic chemistry concepts and can be more successful which is seen in the first exam analysis where minimal errors were seen. The first exam analysis observed minor pentavalent atoms and errors with the EPF arrows (Flynn and Featherstone, 2017). The following interview study found students described mapping, charges, stepwise, and chemistry reasoning when discussing electron movement (Galloway et al., 2017). The findings from this work demonstrated the EPF arrows as a representation are meaningful to participants as they interpreted the EPF arrows after being recently taught. Similar findings at a different institution using a revised curriculum that focuses on the EPF at the beginning of the course found students were more likely to use the EPF arrows and were more likely to provide the correct answer than their counterparts (Crandell et al., 2018; Houchlei et al., 2021). Research at institutions adopting the functional group curriculum reported that students did not find the EPF meaningful (Bhattacharyya and Bodner, 2005; Ferguson and Bodner, 2008; Grove, Cooper, and Rush, 2012). The findings suggest that the time spent mastering the EPF arrows at the beginning of the course is beneficial when learning organic chemistry because the symbols are less likely to be a hindrance through misinterpretation, and students can focus on mastering organic chemistry concepts. Implications for teaching and learning include providing clarity on interpreting the EPF arrows and using the transplanting processes to demonstrate other chemical possibilities. Participants demonstrated comparing reactants and products when problem-solving. When students face difficulty, they should compare the products of chemical processes (bond-forming, bond-breaking, or electrons moving). The correct process has the EPF arrow starting from electrons and point to an atom or bond, maintains the conservation of atoms, and electrons stay with one of the originating atoms. The other processes will not follow one of the above principles, thus making them illogical. Future work could further explore if students interpret the EPF arrows as a whole or if they interpret the arrowhead and arrow tail. Why do some students face difficulty keeping electrons on an originating atom? Why do some students face difficulty conserving atoms, electrons, and charges throughout a reaction? Whether the findings are generalizable by expanding the sample size. In the context of the new curriculum, it appears students' have acquired a better understanding of the EPF. The results are promising because participants with minimal experience interpreted the EPF arrows and found them meaningful as a symbolic representation aligned with the curriculum's intentions.