Student Reasoning and Collaboration Networks in Thermal Physics

Thermal physics courses have received relatively less attention from the field of physics education research than other core physics courses like quantum mechanics or electromagnetism. This thesis is composed of two projects which look at thermal physics courses from different perspectives. The first looks qualitatively at student reasoning in think-aloud interviews on a set of conceptual problems related to entropy. We use a conceptual resources framework to analyze and compare graduate and undergraduate student responses. The set of questions includes both new and previously studied problems and includes a novel system---a string waving in a bath of water---which could be used as a complementary way of introducing students to the concept of entropy. The second project quantitatively examines social networks of students working together on homework assignments in the upper-division thermal physics course at CU Boulder (as well as a middle-division math methods course at the Colorado School of Mines). We calculate the correlation between nodal centrality measures, which quantify how connected a node is to its larger network, and performance to quantify the relationship between collaboration and course grades. Also, we studied the possible effects of systematic errors caused by missing data within networks to better understand the significance of our results.</p

Correlations between student connectivity and academic performance: a pandemic follow-up

Social network analysis (SNA) has been gaining traction as a technique for quantitatively studying student collaboration. We analyze networks, constructed from student self-reports of collaboration on homework assignments, in two courses from the University of Colorado Boulder and one course from the Colorado School of Mines. All three courses occurred during the COVID-19 pandemic, which allows for a comparison between the course at the Colorado School of Mines (in a fully remote format) with results from a previous pre-pandemic study of student collaboration at the Colorado School of Mines (in a hybrid format). We compute nodal centrality measures and calculate the correlation between student centrality and performance. Results varied widely between each of the courses studied. The course at the Colorado School of Mines had strong correlations between many centrality measures and performance which matched the patterns seen in the pre-pandemic study. The courses at the University of Colorado Boulder showed weaker correlations, and one course showed nearly no correlations at all between students' connectivity to their classmates and their performance. Taken together, the results from the trio of courses indicate that the context and environment in which the course is situated play a more important role in fostering a correlation between student collaboration and course performance than the format (remote, hybrid, in-person) of the course. Additionally, we conducted a short study on the effect that missing nodes may have on the correlations calculated from the measured networks. This investigation showed that missing nodes tend to shift correlations towards zero, providing evidence that the statistically significant correlations measured in our networks are not spurious.Comment: Submitted to Phys. Rev. PE

Retrieving the Coassembly Pathway of Composite Cellulose Nanocrystal Photonic Films from their Angular Optical Response.

Aqueous suspensions of cellulose nanocrystals (CNCs) are known to self-assemble into a chiral nematic liquid crystalline phase, leading to solid-state nanostructured colored films upon solvent evaporation, even in the presence of templating agents. The angular optical response of these structures, and therefore their visual appearance, are completely determined by the spatial arrangement of the CNCs when the drying suspension undergoes a transition from a flowing and liquid crystalline state to a kinetically arrested state. Here, it is demonstrated how the angular response of the final film allows for retrieval of key physical properties and the chemical composition of the suspension at the onset of the kinetic arrest, thus capturing a snapshot of the past. To illustrate this methodology, a dynamically evolving sol-gel coassembly process is investigated by adding various amounts of organosilica precursor, namely, 1,2-bis(trimethoxysilyl)ethane. The influence of organosilica condensation on the kinetic arrest can be tracked and thus explains the angular response of the resulting films. The a posteriori and in situ approach is general; it can be applied to a variety of additives in CNC-based films and it allows access to key rheological information of the suspension without using any dedicated rheological technique.M.J.M. thanks NSERC for a Discovery Gran

Research data supporting "Retrieving the co-assembly pathway of composite cellulose nanocrystal photonic films from their angular optical response"

the Summary of the data is detailed in the provided document "OpenDataSummary.pdf" and ordered by the figures they contributed to, including for the Figures in Supporting Information.M.J.M. thanks NSERC for a Discovery Grant