Patterns of reasoning – exploring the interplay of students’ work with a scaffold and their conceptual knowledge in organic chemistry

A deep understanding of organic chemistry requires a learner to understand many concepts and have fluency with multiple skills. This understanding is particularly necessary for constructing and using mechanisms to explain chemical reactions. Electrophilicity and nucleophilicity are two fundamental concepts to learning and understanding reaction mechanisms. Prior research suggests that learners focus heavily on explicit structural features (e.g., formal charge) rather than implicit features (e.g., an open p-orbital) when identifying and describing the role of electrophiles and nucleophiles in reaction mechanisms; however, these findings come from small-scale, interview-based investigations with a limited number of reaction mechanisms. The work reported herein seeks to further explore the meaning learners ascribe to electrophiles and nucleophiles by evaluating 19 936 written explanations from constructed-response items asking what is happening in reaction mechanisms and why it happens for 85 unique reaction mechanisms across a yearlong postsecondary organic chemistry course. To analyze these data, we developed an electrophile rubric to capture learners’ level of explanation sophistication (Absent, Descriptive, Foundational, and Complex); this electrophile rubric is complementary to a nucleophile rubric previously reported in the literature. Our data show proportional levels of explanation sophistication for electrophiles and nucleophiles (τb = 0.402) across these written explanations of reaction mechanisms. We note that learners’ explanations of nucleophiles tend to be at a higher level than their explanations of electrophiles. While this finding does support prior literature reports, we also found that explanations of mechanisms involving reductions of pi-bonds (e.g., carbonyls) tended to be more sophisticated for electrophiles than for nucleophiles. Overall, our results support the claim that learners are able to discuss both electrophilicity and nucleophilicity; however, learners discuss electrophilicity and nucleophilicity at different levels of sophistication where nucleophilicity predominates for most reaction types.

Section: Assessing Reaction Mechanisms Learningmentioning

confidence: 98%

Evaluating electrophile and nucleophile understanding: a large-scale study of learners’ explanations of reaction mechanisms

Frost

Yik

Dood

et al. 2023

“…Taken together, mechanistic reasoning, with or without ML techniques, can only be assessed, if prompts elicit the desired, reasoning skills. Recent studies in chemistry education research have shown the effectiveness of scaffolded prompts (Cooper et al, 2016;Caspari and Graulich, 2019;Graulich and Caspari, 2020;Watts et al, 2021;Kranz et al, 2023). According to these findings, ML-related studies should pay attention to the structure and wording of prompts to collect evidence of mechanistic reasoning.…”

Section: Prompt Structure In Ml-detected Reasoningmentioning

confidence: 99%

When a machine detects student reasoning: a review of machine learning-based formative assessment of mechanistic reasoning

Martin

Graulich

2023

Self Cite

“…This study collected data using semi-structured interviews in the form of case comparison tasks. Case comparison tasks have been previously used to identify all relevant variables to the task (Alfieri et al, 2013) in chemistry education literature (e.g., Kranz et al, 2023). While preparing and organizing semi-structured interviews, we considered not only students' learning experiences during organic chemistry classes but also fundamental concepts required to understand stability, acidity, and basicity.…”

Section: Data Collectionmentioning

confidence: 99%

Organic chemistry students’ use of stability in mental models on acid and base strength

Demirdöğen,

Nelsen,

Lewis

2023

The Brønsted–Lowry acid–base model is fundamental when discussing acid and base strength in organic chemistry as many of the reactions include a competing proton transfer reaction. This model requires evaluating chemical stability via a consideration of electronic granularity. The purpose of this study is to identify students’ mental models on acid and base strength in terms of granularity and stability. Fourteen students enrolled in organic chemistry participated in this case study. Data were collected through semi-structured interviews including total case comparison tasks on stability, acidity, and basicity. Analysis of data revealed that there were four groups of students differentiated by their reasoning: (1) acid and base strength through structure without association to stability, (2) acid and base strength through electronics without association to stability, (3) acid strength associated with electronically centered stability, and (4) acid and base strength associated with electronically centered stability. This characterization can support teaching and research to promote reasoning that leads to a more consistent mental model across acid and base strength.