An understanding of acid–base reactions is necessary for success in chemistry courses and relevant to careers outside of chemistry, yet research has demonstrated that students often struggle with learning acid–base reaction mechanisms in organic chemistry. One response to this challenge is the development of educational applications to support instruction and learning. The development of these supports also creates an opportunity to probe students’ thinking about organic chemistry reaction mechanisms using multiple modalities—i.e., using an app interface or the traditional paper–pencil. This study used think-aloud interviews conducted with undergraduate students in their first semester of organic chemistry to understand how they worked through two acid–base reactions using either paper–pencil or an app. Analysis of the interviews indicates that students from both groups recognize the steps of acid–base reactions, but do not always apply the underlying concepts, such as assessment of pK_a values or resonance, when determining how a reaction will proceed. The modality seemed to somewhat influence students’ thinking, as the app prevented students from making chemically unreasonable mistakes. However, some students relied on the cues it provided, which could potentially be problematic when they are required to respond to assessments that do not provide these cues. Our results suggest that instructors should emphasize the conceptual grounding for the steps that govern acid–base reactions to promote chemical thinking about the relationships between the reaction components and how those influence reaction outcomes, as well as support students to think critically about the chemical information contained within the modalities they are using.

Organic chemistry is a required course sequence for many STEM students, however research indicates that organic chemistry reaction mechanisms are especially challenging for students due to a mixture of underlying conceptual difficulties, the process-oriented thinking inherent to the discipline, and the representations commonly used to depict mechanisms. While student reasoning about many of the reaction types covered in the organic chemistry curriculum have been studied previously, there is minimal research focused specifically on how students think about the mechanisms of addition reactions. This study addresses that gap by probing first semester organic chemistry students' thinking using think-aloud interviews as they worked through two different addition reactions. To elicit a range of thinking, students worked through the mechanisms using either paper and pencil or an app that dynamically represents the molecules. Overall, students were able to identify the steps of the two addition reactions but did not always successfully apply chemical thinking during the mechanistic steps. Specifically, both groups of students struggled with the concepts related to carbocation stability, frequently misapplying stabilization via substitution and demonstrating difficulty in identifying the potential for resonance stabilization. Our results suggest that instructors should emphasize the conceptual grounding directing mechanistic steps, in particular when determining carbocation stability.

Lewis structures are fundamental to learning chemistry, yet many students struggle to develop a complex understanding of its meaning and uses. Writing-to-Learn supports students in developing a deeper conceptual understanding of the topic, making it an ideal pedagogy to apply to student learning of Lewis structures. One difficulty often associated with classroom writing is the capacity of instructors to provide feedback to each student on their written work; however, this practical constraint can be mitigated through incorporating peer review. Peer review and revision are known to support conceptual learning and yet are underutilized in STEM (Science, Technology, Engineering, and Math) classrooms. Additionally, peer review is an authentic, common, and necessary practice in chemistry research, which warrants its incorporation early on in chemistry courses. A major concern regarding the use of peer review-based feedback is the ability of students to provide concept-based feedback that is both correct and detailed enough to enhance student understanding and support substantial revisions. In response, this work investigates the relationship between revision and the characteristics of students’ peer review comments in the context of a Writing-to-Learn assignment focusing on student understanding of Lewis structures. Chemistry students wrote a summary of Lewis’ 1916 paper introducing Lewis structures, participated in peer review, and revised their work in response to a structured prompt detailing specific chemistry concepts to be covered. The peer review comments and students’ revisions were thematically analyzed. The peer review comments were deductively analyzed according to an analytical framework to characterize the usefulness of comments. The extent and type of student revisions were also analyzed and paired, if relevant, with the associated peer review comments. Results indicate that students provided both detailed and conceptually focused comments on their peers’ work, irrespective of specific chemistry content being addressed. Although the assignment and peer review rubric were content focused, students made a mixture of editing and content revisions following peer review. These results suggest that further scaffolding of what constitutes good feedback and revision may further promote student learning.