Students’ Mechanistic Explanations across Undergraduate Chemistry and Biology Courses

Jon Stoltzfus
Biological Sciences Program Director
Michigan State University

Need:Constructing useable cross-disciplinary knowledge is essential if STEM graduates are to address societal challenges such as pandemics or climate change. However, curricula at large universities rarely connect courses across disciplines in ways that are obvious to students, and little is known about how students connect learning across disciplines. Designing curricula that connect across courses requires understanding if and how instruction supports students in developing and using knowledge from various disciplines. Guiding Questions:Our work is based on Hammer’s resource perspective on student learning, the three-dimensional learning framework for science education, and Krist’s framework for mechanistic explanations. We focus on the scientific practice of constructing explanations and the crosscutting concept of cause and effect using two chemistry core ideas (electrostatic interactions and molecular structure and properties), and three biology core ideas (structure and function, information flow, and evolution). We asked students how and why two proteins have different functions and how and why this can influence evolution. Our research questions are: (1) how do we develop a task that elicits causal mechanistic reasoning across disciplines? (2) what conceptual resources do students use as they respond to this task and, if causal mechanistic reasoning is present, how do students link these conceptual resources into causal mechanistic explanations? (3) how do specific task details influence the conceptual and epistemic resources students use in their response? and, (4) how does resource use differ at different points in a life sciences curriculum? Outcomes:Our work highlights the difficulty of developing cross-disciplinary tasks and the influence of task details on which conceptual and epistemic resources students use and reinforces the importance of iterative cycles of task development. Our results show that some undergraduate students in a life-sciences curriculum use a causal mechanistic explanation epistemic framework in response to our tasks, but many do not. In addition, while some students incorporate ideas from biology or chemistry, individual students rarely incorporate concepts from both disciplines. Finally, we show how the conceptual resources used and the frequency with which students use a causal mechanistic reasoning frame varies at different points in a STEM curriculum. Based on our results, the research tasks and coding schemes developed in this study can guide creation of formative or summative assessments that help instructors understand students’ mechanistic explanations across chemistry and biology. However, more work is needed to support students in constructing causal mechanistic explanations and in connecting ideas across chemistry and biology. Broader Impacts:This project shows the conceptual and epistemic resources found in student responses to a task requiring integration across chemistry and biology and provides insights on supporting learning across these disciplines. It provides a starting point for assessing if students construct mechanistic explanations and if and how students connect ideas across these disciplines. Iterative development of these assessments and the common framework, language, and instructional strategies they provide will help instructors better support construction of usable cross-disciplinary knowledge so students can take on complex, cross disciplinary challenges when they graduate.


Caleb M. Trujillo, University of Washington Bothell, Washington; Christina V. Schwarz, Michigan State University, Michigan; Clare Carlson, Michigan State University, Michigan; Devin Babi, Michigan State University, Michigan; Elijah Persson-Gordon, Michigan State University, Michigan; Estefany Beltran-Flores, Michigan State University, Michigan; Jenna Kesh, Michigan State University, Michigan; Joelyn de Lima, Michigan State University, Michigan; Keenan Noyes, Michigan State University, Michigan; Melanie M. Cooper, Michigan State University, Michigan; Robby McKay, Michigan State University, Michigan; Seth Hunt, Michigan State University, Michigan; Tammy M. Long, Michigan State University, Michigan;