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Laboratory experimentation is a key component of the development of professional engineers. However, experiments conducted in chemical engineering laboratory classes are commonly more prescriptive than the problems faced by practicing engineers, who have agency to make consequential decisions across the experiment and communication of results. Thus, understanding how experiments in laboratory courses vary in offering students opportunities to make such decisions, and how students navigate higher agency learning experiences is important for preparing graduates ready to direct these practices. In this study, we sought to answer the following research questions: How do students perceive their agency in course-based undergraduate research experiences? What factors are measured by the Consequential Agency in Laboratory Experiments survey? To better understand student perceptions of their agency in relation to laboratory experiments, we first conducted a case study of a course-based research experience (CURE) in a senior-level chemical engineering laboratory course. We then surveyed six upper-division laboratory courses across two universities using an initial version of the Consequential Agency in Laboratory Experiments survey. We used exploratory factor analysis to investigate the validity of the data from the survey for measuring relevant constructs of authenticity, agency in specific domains, responsibility, and opportunity to make decisions. We found that with instructional support, students in the CURE recognized that failure could itself provide opportunities for learning. They valued having the agency to make consequential decisions, even when they also found the experience challenging. We also found strong support for items measuring agency as responsibility, authenticity, agency in the communication domain, agency in the experimental design domain, and opportunity to make decisions. These findings give us insight into the value of higher agency laboratory experiments, and they provide a foundation for developing a more precise survey capable of measuring agency across various laboratory experiment practices. Such a survey will enable future studies that investigate the impacts of increasing agency in just one domain versus in several. In turn, this can aid faculty in developing higher agency learning experiences that are more feasible to implement, compared to CUREs.
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Manipulating Dendritic Growth: An Undergraduate Laboratory Experience with the Interplay between Mass Transport, Supersaturated Solutions, and Dendrite Structure
Dendrite growth affects material systems across applications as diverse as lithium batteries, organic light emitting diodes, turbine blades, and biological sensors. Their unique crystal structure and ability to physically see growth make for a unique undergraduate laboratory experience. This experiment uses dendrite growth to explore the physical and chemical driving forces behind dendrite growth through a set of viscous, supersaturated solutions of varying ammonium chloride and gelatin concentrations. The degree of NH4Cl supersaturation determines growth rate, which can be mediated by the gelatin limiting diffusional mass transfer. This exercise was designed for a material science course, though it could easily be adapted to an inorganic or general chemistry course. Through this experiment, students are introduced to optical microscopy for quantitative analysis, a common, inexpensive analytical research tool rarely seen in the undergraduate laboratory. When chemical driving forces are dominant (low gelatin, high salt concentrations), a more ordered dendrite structure forms, with primary branches at 90° angles. Conversely, as diffusion becomes more dominant, a more disordered, denser dendrite structure is observed and the growth rate is slower. Students use both qualitative and quantitative observations to make connections between a fundamental laboratory exercise and critical materials processing techniques that rely on physicochemical driving forces.
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- Award ID(s):
- 1727316
- PAR ID:
- 10164106
- Date Published:
- Journal Name:
- Journal of chemical education
- Volume:
- 97
- Issue:
- 2
- ISSN:
- 1050-4281
- Page Range / eLocation ID:
- 503-508
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1021/acs.jchemed.8b00962
