Relevance and equity: should stoichiometry be the foundation of introductory chemistry courses?

Abstract

Emphasizing stoichiometry appears to be a norm of introductory chemistry courses. In this longitudinal and mixed-methods study, we examined how the emphasis on stoichiometry in assessments of introductory chemistry impacted...

Evaluating and Improving Questions on an Unproctored Online General Chemistry Exam

“…A potential concern with the open-response format was that performance would not be equitable for all students. The mole and stoichiometric conversions have been identified as two of the most frequently assessed and inequitable competencies in general chemistry, perpetuating systemic inequalities in access to precollege mathematics preparation . Analysis of conceptual inventories have also identified problematic questions in terms of item-level gender fairness, − and it was possible the modified format would heighten performance differences based on student descriptors of gender, under-represented minority (URM) status, or first-generation college (FGEN) status.…”

“…The mole and stoichiometric conversions have been identified as two of the most frequently assessed and inequitable competencies in general chemistry, perpetuating systemic inequalities in access to precollege mathematics preparation. 47 Analysis of conceptual inventories have also identified problematic questions in terms of item-level gender fairness, 48−50 and it was possible the modified format would heighten performance differences based on student descriptors of gender, under-represented minority (URM) status, or first-generation college (FGEN) status. To investigate this concern, mean performance differentials were calculated for these student descriptors as fixed factors in a univariate analysis in which the question was the dependent variable and the overall exam performance a covariate.…”

Assessment of Scientific Practice Proficiency and Content Understanding Following an Inquiry-Based Laboratory Course

“…This finding, 72% of students conducted a respectable titration, is noteworthy. The issues students had with using stoichiometry in this calculation again highlights the need to focus on conceptual understanding of stoichiometric calculations within the scientific practice rather than mathematical manipulations. ,− …”

“…Ratios were often “flipped” which is likely a result of students incorrectly applying a mathematical model rather than the incorrect product (CuO) and reactant (Cu or Cu 2 O). , The required stoichiometric calculations to obtain the theoretical yield, were problematic with 41% (Table , Q 1.5) of the students having an incorrect value for theoretical yield. The unique challenges students have with stoichiometry have been well documented, ,− yet at most institutions these calculations are a cornerstone of first-semester general chemistry.…”

“…By assessing student chemistry concept knowledge and scientific practice proficiency in this way, it is possible to suggest ways to improve student understanding in future iterations of the course, such as focusing more on the conceptual aspects of stoichiometry or to change course learning outcomes to reflect the current research on stoichiometric calculations. 8,28 The scores on the IDEAA-GC1 highlighted ways that the practical exam could be modified. The Constructing an Argument f rom Evidence items (Figure 5) suggested that students were more proficient with providing a claim than they were with evidence and justification.…”