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Representations in chemistry are the tools by which students, instructors, and chemists reason with chemical concepts that are abstract. Although representations are regularly used within the chemistry classroom, there is more to uncover regarding the ways students interact with representations when given chemistry tasks. This study aimed to address this gap in knowledge. In this study, eighteen students enrolled in second semester general chemistry were recruited for data collection. Semi-structured interviews were utilized to observe how students approached a similar set of dipole–dipole interaction tasks when given four distinct representations. Analysis of the data revealed that students’ approaches to these tasks were affected by the newly explicit features present within each representation. Additionally, the ordering in which the representations were presented to the students influenced the specific features students took notice of and implemented into their approaches to the tasks. These findings can better inform instruction and future research involving chemical representations such that students will form a solid foundation in working with and pulling relevant information from various representations when solving chemistry tasks. 

Studies investigating chemistry students’ understanding of intermolecular forces have listed alternative conceptions; however, there is a call to investigate why students might have these alternative conceptions. This study describes how second semester general chemistry students predict the location of dipole–dipole forces between two molecules from a resource activation perspective. During interviews, 18 students were asked to describe the location of forces between four pairs of molecules. Students relied on one or more of the following approaches in determining location: (1) attraction between opposite charges, (2) electronegativity differences, (3) biggest electronegativity values, (4) largest atomic size, and (5) molecular shape. Each student’s approach is characterized by the resources being activated and, in particular, students’ use of electronegativity. Students’ use of electronegativity varied, including comparing electronegativity values between unbonded atoms within a molecule and between atoms present on different molecules. The findings suggest future research directions and teaching implications that could improve students’ understanding of intermolecular forces including the explicit integration and assessment of the concepts of electronegativity and intermolecular forces. 

Education in organic chemistry is highly reliant on molecular representations. Students abstract information from representations to make sense of submicroscopic interactions. This study investigates relationships between differing representations: bond-line structures, ball-and-stick, or electrostatic potential maps (EPMs), and predicting partial charges, nucleophiles, and electrophiles. The study makes use of students’ answers in hot-spot question format, where they select partially charged atoms on the image of a molecule and explanations. Analysis showed no significant difference among students when predicting a partially positive atom with each representation; however, more students with EPMs were able to correctly predict the partially negative atom. No difference was observed across representations in students predicting electrophilic character; while representations did influence students identifying nucleophilic character. The affordance of EPMs was that they cued more students to cite relative electronegativity indicating that such students were able to recognize the cause for electron rich/poor areas. This recognition is central to rationalizing mechanisms in organic chemistry. This study offers implications on incorporating EPMs during instruction and provides evidence-based support in how EPMs could be useful in promoting learning on topics that relate to an uneven charge distribution. 

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. 

Conceptually understanding chemistry requires the ability to transition among representational levels to use an understanding of submicroscopic entities and properties to explain macroscopic phenomena. Past literature describes student struggles with these transitions but provides limited information about upper-level post-secondary chemistry students’ abilities to transition among levels. This group is of particular interest as they are engaging in potentially their final training before entering a career as professional chemists, thus if students are likely to develop this skill during their formal education it should be manifest among this group. This study characterized analytical chemistry students’ responses to open-ended assessments on acid–base titrations and thin-layer chromatography for the use of sub-microscopic entities or properties to explain these macroscopic phenomena. Further, to understand whether explanatory statements were an expectation inherent in the instructional context of the setting, the analytical chemistry instructor's lectures on acid–base titrations and thin-layer chromatography were analyzed with the same framework. The analysis found that students seldom invoked explanatory statements within their responses and that congruence between lectures and responses to assessment was primarily limited to the use of macroscopic, descriptive terms. Despite the fact that the lecture in class regularly invoked explanatory statements in one context, this did not translate to student use of explanatory statements. To further test the hypothesis that analytical chemistry students struggle with explanatory statements, a follow-on study was also conducted among a second cohort of students reviewing their responses when specifically prompted to use sub-microscopic entities to explain a macroscopic phenomenon. The results suggest that fewer than half of the students showed proficiency on generating explanatory statements when explicitly prompted to do so. Instructional implications to promote explanatory statements are proposed in the discussion. 

Students who score within the bottom quartile on cognitive measures of math aptitude have been identified as at-risk for low performance in chemistry courses, with less attention as to why such differential performance persists. At-risk students struggle most differentially on assessment items related to the mole concept and stoichiometry. An exploration as to the nature of the differential performance observed became of great interest as the assessment of these topics rarely progresses beyond multiplication or division, and at-risk students who achieved proficiency with the mole concept and stoichiometry had no noticeable gaps in academic chemistry performance when compared to students scoring in the top three quartiles of math aptitude. Thus, students in first-semester general chemistry were surveyed to describe their solution processes toward assessment items involving the mole concept and stoichiometry. Three hundred and forty-eight students responded to all survey prompts with 101 identified as at-risk. Findings suggest that while all students were observed to struggle in the conceptualization of the algorithms by which they execute solution processes, not-at-risk chemistry students were more likely to achieve correct answers via chemically implausible solution pathways. Rather than suggest the removal of assessment practices involving algorithmic, multiple-choice assessment on these topics, the implications include practical suggestions and opportunities for further research toward improving the equitability of measures used to assess proficiency with stoichiometry. 

Investigating the effectiveness of instructional practices provides an evidence base to inform instructional decisions. Synthesizing research studies on instructional effectiveness provides an estimate of the generalizability of effectiveness across settings, along with an exploration of factors that may moderate the impact, which cannot be achieved within individual studies. This study sought to provide a synthesis of evidence‐based instructional practices (EBIPs) particular to chemistry through meta‐analysis. Ninety‐nine studies were analyzed comprising a broader view of chemistry specific studies than past meta‐analyses. The results showed that EBIPs feature a demonstrably positive impact on students' academic performance in chemistry, although assessment topic coverage and setting size emerged as relevant moderators of impact and prevented making definitive conclusions of the relative impact of each EBIP. In examining publication bias, an asymmetric distribution of studies based on standard error(SE)and effect size was found, indicative of potential publication bias. To explore the potential impact of bias, the trim and fill method was employed resulting in a range for the overall weighted effect size from 0.29 to 0.62. The study concludes that evidence‐based instructional practices have demonstrated effectiveness even in consideration of potential publication bias, as the range of effect sizes remains positive, but highlights the continued need to publish null findings in the research literature.