<p>Delocalization (resonance) is a concept in organic chemistry that influences the chemical reactivity, structure, and physical properties of molecules. However, the concept has proven challenging for students and the related learning outcomes had previously been only vaguely defined. We recently defined ten essential learning outcomes about delocalization that a student should be able to demonstrate by the end of a two-course organic chemistry sequence. The goal of the present study was to investigate to what extent the ten LOs were achieved by students, as well as the connections between the LOs. We analyzed three exam questions related to seven of the ten LOs for the degree of achievement, common errors, and scientific reasoning. We found that students sometimes struggled to identify when delocalization could occur, that some of the LOs built on one another, and that students were more successful in drawing resonance structures when explicitly asked, but less successful when the requirement was implicit or embedded within a mechanism. Our analysis of student reasoning showed that the dominant modes of reasoning were aligned with the related expectations and explanations in the course. When asked to justify the contribution of resonance structures to the resonance hybrid, most answers used a descriptive mode of reasoning; when asked to explain why a given proton was more acidic than another, most answers contained relational and linear causal reasoning. Implications for research and practice are discussed.</p>

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.

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.

<p>Delocalization (resonance) is a concept in organic chemistry that influences the chemical reactivity, structure, and physical properties of molecules. However, the concept has proven challenging for students and the related learning outcomes had previously been only vaguely defined. We recently defined ten essential learning outcomes about delocalization that a student should be able to demonstrate by the end of a two-course organic chemistry sequence. The goal of the present study was to investigate to what extent the ten LOs were achieved by students, as well as the connections between the LOs. We analyzed three exam questions related to seven of the ten LOs for the degree of achievement, common errors, and scientific reasoning. We found that students sometimes struggled to identify when delocalization could occur, that some of the LOs built on one another, and that students were more successful in drawing resonance structures when explicitly asked, but less successful when the requirement was implicit or embedded within a mechanism. Our analysis of student reasoning showed that the dominant modes of reasoning were aligned with the related expectations and explanations in the course. When asked to justify the contribution of resonance structures to the resonance hybrid, most answers used a descriptive mode of reasoning; when asked to explain why a given proton was more acidic than another, most answers contained relational and linear causal reasoning. Implications for research and practice are discussed.</p>