The Implementation of Visualization Aids to Help Students with Structural Isomerism
Authors:   , Pesce Adrienne M. , King Daniel B. , Ji Haifeng 
Published: November 2024

Student struggles with visually demanding chemistry topics have been documented for decades. Recommendations to help students master these topics include implementation of visual aids, such as molecular models. While there are some studies on the effects of molecular model usage, these studies were conducted with students who had already completed the course in which the target topic was taught. Few studies exist that explored the effect of implementing an intervention with deliberate molecular model usage during the initial content introduction. Of particular interest is the topic of isomerism, a historically difficult topic for novice chemists that relies on a student's ability to interpret three-dimensional structures. A commonly suggested remedy is an increased deliberate use of molecular model kits, a staple recommendation on many organic chemistry syllabi for decades. Despite this widespread recommendation, this visualization tool is rarely used by students. Anecdotally, students have indicated that they either did not know how to use the model kits or that they did not think they would be helpful. Item Analysis of the Fall 2018 and Winter 2019 exams for CHEM103, an introductory organic chemistry course, revealed that the structural isomerism exam questions were of significant difficulty for students; additionally this was the first isomerism topic presented to students. The activity created as part of this study was designed with a two-fold goal: 1) engage students in solving structural isomerism problems, and 2) introduce students to a mobile device molecular modeling tool. Analyses of the Fall 2021 and Winter 2022 exams for CHEM103 showed a significant score improvement on a post-activity assessment when compared to a pre-activity assessment. This improvement was observed for both quarters, despite differences in the cohorts' prior course work. However, for the Fall 2021 and Winter 2022 cohorts, a structural isomerism exam question, analogous to the one examined in Fall 2018 and Winter 2019, no longer ranked as significantly difficult on the exam after completion of the activity. We wanted to determine if there was a difference in the effectiveness of the activity using a mobile app or a traditional ball-and-stick model kit. The Spring 2022 cohort was divided into three equivalent groups, each completing a slightly different version of the activity. Group 1 used no visual aids; Group 2 used the ModelAR mobile device application; and Group 3 used a traditional ball-and-stick model kit. Despite all three groups scoring equivalently on the pre-activity assessment, only Groups 1 and 2 showed a score improvement on the post-activity assessment, with only Group 2 showing a significant improvement at the 95% confidence limit. Prior to the start of the quarter, students completed the Purdue Spatial Visualization Test: Rotations (PSVT:R), and the corresponding scores were used to divide students into visualization skill tiers. We found that the low visualization skill tier for both Group 1 and Group 2 in Spring 2022 showed a significant score improvement on the post-activity assessment with respect to the pre-activity assessment. Additionally, in the case of Group 2, the low visualization tier scored equivalently to the moderate visualization tier and the high visualization tier on the post-activity assessment. This is consistent with the data collected from the Fall 2021 cohort and the Winter 2022 cohort. For Group 1, there was a significant performance gap on the post-activity assessment scores between the low visualization tier and the moderate and high visualization tiers. These data indicate that while time-on-task likely improves post-activity assessment scores, especially for low visualization skill students, the Group 1 students were still unable to perform at the same level as their higher visualization level peers. The inclusion of the mobile device modeling application, ModelAR, lead to the closing of the performance gap between the lower visualization students and their higher visualization-level peers. In the case of Group 3, those who used a traditional hand-held ball-and-stick model kit, only the low visualization students saw any improvement, which was not statistically significant. Both the high visualization and moderate visualization tiers saw their average scores decrease slightly on the post-activity assessment compared to the pre-activity assessment. We hypothesize that a contributing factor for this observation is that students were distracted by the physical assembly and disassembly associated with the physical models. This project demonstrated the positive effect of implementing a short structural isomerism activity on student performance on a post-activity assessment and on an in-class exam question. Additionally, this project showed that while additional time-on-task can improve student performance, the inclusion of a virtual model kit led to a significant improvement in that performance, particularly for students with low visualization skills.