An examination of pre-service chemistry teachers’ meaningful understanding and learning difficulties about aromatic compounds using a systemic assessment questions diagram

Abstract

In order for students to reach a level of meaningful understanding of chemistry, it is vital that they are able to form accurate relationships between different concepts. In particular, in organic chemistry, identifying intermolecular reactions, considering these reactions as a whole, and defining their results will make important contributions to attaining meaningful understanding. This study aims to explore how pre-service chemistry teachers identify aromatic compound reactions and form associations between them and to discover what kinds of learning difficulties they encounter in forming these associations. In this context, the study, conducted as phenomenographical research, was carried out at a faculty of education in Turkey with 15 pre-service teachers enrolled in the Department of Chemistry Education who had taken the Organic Chemistry 1 and 2 courses. Selected on the basis of purposive sampling, the pre-service chemistry teachers were first asked systemic assessment questions (SAQs) related to aromatic compound reactions. In these questions, the pre-service chemistry teachers were asked to identify 7 molecules in the class of aromatic compounds and complete a diagram by taking into consideration synthesis and reaction conditions. The pre-service chemistry teachers were also asked to indicate two reactions that were not included in the SAQs diagram, together with their reagents and conditions. After completing their responses to the SAQs diagram, individual interviews were held with each of the pre-service chemistry teachers using the think-aloud technique. The research revealed at the end of the quantitative analysis of the data obtained from the SAQs diagram that most of the pre-service chemistry teachers achieved moderate-level scores. At the same time, the qualitative analysis of the data obtained from the SAQs diagram and from the interviews showed that the pre-service chemistry teachers were more successful in identifying and forming associations with the reactions of “nitration” and “sulfonation of aromatic compounds” but had difficulty with the “Friedel–Crafts alkylation,” “oxidation” and “reduction” reactions and with the “bromination of alkenylbenzenes” and the “addition reaction of the double bond of alkenylbenzenes.” Another important finding resulting from this study was that only a few pre-service chemistry teachers were able to identify a new reaction on the SAQs diagram. All of these findings indicate that the pre-service teachers are not very equipped to form meaningful relationships in the context of aromatic compounds, which is one of the basic topics of organic chemistry.

Mechanistic Reasoning in Organic Chemistry: A Scoping Review of How Students Describe and Explain Mechanisms in the Chemistry Education Research Literature

“…Teleological and anthropomorphic reasoning closely relate to aspects of the reasoning processes framework used to characterize students’ reasoning in the organic chemistry education literature (the framework is sometimes referred to as the “modes of reasoning framework”, but is referred to as the “reasoning processes framework” to distinguish it from the other modes of reasoning framework). ,, The framework includes rules-based reasoning (the use of rules, often memorized, to explain phenomena; RBR), case-based reasoning (matching a problem to a similar, memorized case; CBR), and symbol-based reasoning (the manipulation of chemical symbols to reason about phenomena; SBR). ,, RBR, CBR, and SBR all reflect the surface-level reasoning characteristic of teleological and anthropomorphic reasoning. Of these three, reasoning based on memorized rules is frequently noted in the literature. ,− ,,,,− ,,− All three reasoning processes contrast with models-based reasoning (MBR), which is the use of a working mental model of a phenomenon that can be applied to dynamic situations (e.g., a mental model for determining the reaction pathway for substitution and elimination reactions). ,, MBR is similar to models and modeling frameworks, − which other researchers have used to interpret students’ mental models of reaction mechanisms and the related chemical concepts. ,,,,, Students’ more sophisticated mental models are akin to mechanistic and causal reasoning, which are common reasoning strategies described in the literature pertaining to students’ explanations of organic chemistry reaction mechanisms.…”

“…62,87−89 Additionally, both undergraduate and graduate students can correctly predict the product without using the EPF or can reproduce the EPF for specific reactions from memory, often without being able to explain the underlying chemical concepts. 46,49,50,59,60,73,80,90,91 Furthermore, when students are unable to recall a mechanism from memory or face an unfamiliar mechanism, they struggle to predict the products using conceptual understanding. 59,73,90,92 Further evidence suggests that many students at both the undergraduate and graduate levels may struggle to make the connection between the notation of the EPF and the electron movement it represents.…”

“…93,98 Some studies have indicated that students especially face challenges with understanding electrophiles. 50,93,97 Challenges with electrophiles may be due to instructional emphasis on nucleophiles, which leaves electrophiles as "simply the other starting material in the reaction" (ref 93, p. 800). This is reflected in how students often describe reactions with the nucleophile doing the action, which places emphasis on the nucleophile.…”

“…20 Students commonly invoke the trend that more substituted carbocations are more stable as the sole reason for determining carbocation stability, often without providing chemical reasoning (such as hyperconjugative effects); students occasionally misremember the trend and incorrectly determine carbocation stability. 20,21,29,38,50,52,81 However, students can exhibit deeper understanding of influences on carbocation stability, such as hyperconjugation or induction. 35,74 Researchers have described various approaches to support students' chemical reasoning about carbocation stability beyond the number-of-substituents argument; these approaches have elicited students' reasoning with properties including the size of substituents, resonance, partial charges, and inductive effects.…”

Feedback loop reasoning in physiological contexts

“…The students were free to take notes and their statements were audio-taped. The test leaders only intervened if the participants forgot to express their thoughts aloud, aside from that, no coach guided their individual thinking-aloud processes (Neubrand and Harms 2017;Sendur 2020). The advantage of thinking-aloud protocols compared to retrospective interviews is that this data collection method capture students' learning processes more accurately (Hu and Gao 2017).…”