Ten Essential Delocalization Learning Outcomes: How Well Are They Achieved?

OBJECTIVE: Delocalization (resonance) is a concept in organic chemistry that influences the chemical reactivity, activity, structure, and physical properties of molecules. However, the concept has proven challenging for students. The goal of the present study was to investigate to what extent ten essential delocalization learning outcomes (LOs) were achieved by students, how students use and reason about delocalization as well as the connections between the LOs. The goal is to discover where and how students may be struggling when answering delocalization-related exam questions and uncover potential barriers to learning delocalization. METHODS: We analyzed students’ responses (N = 3787) on twelve exam questions related to seven of the ten LOs for the degree of achievement, common errors, and scientific reasoning. RESULTS: The achievement on the LOs was variable. We report types of errors and strategies used, the errors are primarily related to drawing resonance structures or the resonance. Six key findings emerged from the analysis: (1) the majority of answers had few (<10%) representational errors (2) in an implicit question where delocalization or inductive effect concepts could be used to justify a response, half the students used delocalization concepts, (3) delocalization was used in 10–20% of answers when relevant but not prompted or required, (4) strategies that helped students reason with the representations (i.e., drawing out electrons or expanding a structure) were correlated with higher achievement of the LOs, (5) students’ reasoning aligned with course expectations, and (6) students who achieved later LOs typically (60–95%) also achieved LO1 and LO2 (Identify that electron delocalization is relevant, Draw resonance structures). CONCLUSIONS: The findings have implications on how students achieve the LOs and suggest ways educators can better support learners with the tools to achieve the LOs. IMPLICATIONS: The findings from this work could be used to design and evaluate new teaching techniques or materials, including scaffolding concepts. Further investigations could lead to a deeper understanding of students’ mental models and thought processes related to delocalization concepts.