Developing an Analytical Framework to Characterize Student Reasoning about Complex Processes

Examining and Supporting Mechanistic Explanations Across Chemistry and Biology Courses

Causal mechanistic reasoning is a thinking strategy that can help students explain complex phenomena using core ideas commonly emphasized in separate undergraduate courses, as it requires students to identify underlying entities, unpack their relevant properties and interactions, and link them to construct mechanistic explanations. As a crossdisciplinary group of biologists, chemists, and teacher educators, we designed a scaffolded set of tasks that require content knowledge from biology and chemistry to construct nested hierarchical mechanistic explanations that span three scales (molecular, macromolecular, and cellular). We examined student explanations across seven introductory and upper-level biology and chemistry courses to determine how the construction of mechanistic explanations varied across courses and the relationship between the construction of mechanistic explanations at different scales. We found non-, partial, and complete mechanistic explanations in all courses and at each scale. Complete mechanistic explanation construction was lowest in introductory chemistry, about the same across biology and organic chemistry, and highest in biochemistry. Across tasks, the construction of a mechanistic explanation at a smaller scale was associated with constructing a mechanistic explanation for larger scales; however, the use of molecular scale disciplinary resources was only associated with complete mechanistic explanations at the macromolecular, not cellular scale.

Missed connections: Exploring features of undergraduate biology students' knowledge networks relating gene regulation, cell-cell communication, and phenotypic expression

Explaining biological phenomena requires understanding how different processes function and describing interactions between components at various levels of organization over time and space in biological systems. This is a desired competency yet is a complicated and often challenging task for undergraduate biology students. Therefore, we need a better understanding of their integrated knowledge regarding important biological concepts. Informed by the theory of knowledge integration and mechanistic reasoning, in this qualitative case study, we elicited and characterized knowledge networks of nine undergraduate biology students. We investigated students' conceptions of and the various ways they connect three fundamental subsystems in biology: 1) gene regulation, 2) cell-cell communication, and 3) phenotypic expression. We found that only half of the conceptual questions regarding the three subsystems were answered correctly by the majority of students. Knowledge networks tended to be linear and unidirectional, with little variation in the types of relationships displayed. Students did not spontaneously express mechanistic connections, mainly described undefined, cellular, and macromolecular levels of organization, and mainly discussed unspecified and intracellular localizations. These results emphasize the need to support students' understanding of fundamental concepts, and promoting knowledge integration in the classroom could assist students' ability to understand biological systems.

The Impact of Context on Students' Framing and Reasoning about Fluid Dynamics

Contextual features of assessments can influence the ideas students draw from and the ways they assemble knowledge. We used a mixed-methods approach to explore how surface-level item context impacts student reasoning. In study 1, we developed an isomorphic survey to capture student reasoning about fluid dynamics, a crosscutting phenomenon, in two item contexts (blood vessels, water pipes), and administered the survey to students in two different course contexts: human anatomy and physiology (HA&P) and physics. We observed a significant difference in two of 16 between-context comparisons and a significant difference in how HA&P students responded to our survey compared with physics students. In study 2, we conducted interviews with HA&P students to explore our findings from study 1. Using the resources and framing theoretical framework, we found that HA&P students responding to the blood vessel protocol used teleological cognitive resources more frequently compared with HA&P students responding to the water pipes version. Further, students reasoning about water pipes spontaneously introduced HA&P content. Our findings support a dynamic model of cognition and align with previous work suggesting item context impacts student reasoning. These results also underscore a need for instructors to recognize the impact of context on student reasoning about crosscutting phenomena.

Oaks to arteries: the Physiology Core Concept of flow down gradients supports transfer of student reasoning

The Physiology Core Concept of flow down gradients is a major concept in physiology, as pressure gradients are the key driving force for the bulk flow of fluids in biology. However, students struggle to understand that this principle is foundational to the mechanisms governing bulk flow across diverse physiological systems (e.g., blood flow, phloem sap flow). Our objective was to investigate whether bulk flow items that differ in scenario context (i.e., taxa, amount of scientific terminology, living or nonliving system) or in which aspect of the pressure gradient is kept constant (i.e., starting pressure or pressure gradient) influence undergraduate students' reasoning. Item scenario context did not impact the type of reasoning students used. However, students were more likely to use the Physiology Core Concept of "flow down [pressure] gradients" when the pressure gradient was kept constant and less likely to use this concept when the starting pressure was kept constant. We also investigated whether item scenario context or which aspect of the pressure gradient is kept constant impacted how consistent students were in the type of reasoning they used across two bulk flow items on the same homework. Most students were consistent across item scenario contexts (76%) and aspects of the pressure gradient kept constant (70%). Students who reasoned using "flow down gradients" on the first item were the most consistent (86, 89%), whereas students using "pressures indicate (but don't cause) flow" were the least consistent (43, 34%). Students who are less consistent know that pressure is somehow involved or indicates fluid flow but do not have a firm grasp of the concept of a pressure gradient as the driving force for fluid flow. These findings are the first empirical evidence to support the claim that using Physiology Core Concept reasoning supports transfer of knowledge across different physiological systems.NEW & NOTEWORTHY These findings are the first empirical evidence to support the claim that using Physiology Core Concept reasoning supports transfer of knowledge across different physiological systems.

What a Difference in Pressure Makes! A Framework Describing Undergraduate Students' Reasoning about Bulk Flow Down Pressure Gradients

Pressure gradients serve as the key driving force for the bulk flow of fluids in biology (e.g., blood, air, phloem sap). However, students often struggle to understand the mechanism that causes these fluids to flow. To investigate student reasoning about bulk flow, we collected students' written responses to assessment items and interviewed students about their bulk flow ideas. From these data, we constructed a bulk flow pressure gradient reasoning framework that describes the different patterns in reasoning that students express about what causes fluids to flow and ordered those patterns into sequential levels from more informal ways of reasoning to more scientific, mechanistic ways of reasoning. We obtained validity evidence for this bulk flow pressure gradient reasoning framework by collecting and analyzing written responses from a national sample of undergraduate biology and allied health majors from 11 courses at five institutions. Instructors can use the bulk flow pressure gradient reasoning framework and assessment items to inform their instruction of this topic and formatively assess their students' progress toward more scientific, mechanistic ways of reasoning about this important physiological concept.

Understanding Homeostatic Regulation: The Role of Relationships and Conditions in Feedback Loop Reasoning

Understanding homeostasis is a goal of biology education curricula, as homeostasis is a core feature of living systems. Identifying and understanding the underlying molecular feedback mechanisms appear to be challenging for students. Understanding the properties and mechanisms of such complex homeostatic systems requires feedback loop reasoning, which is a part of systems thinking. Novices seem to struggle to 1) consider more than one initiating condition in cause-effect relationships and 2) track cause and effect across a sequence of processes. In this cross-sectional study, we analyzed how these factors impede feedback loop reasoning. High school and undergraduate students analyzed the organizational, behavioral, and modeling-related features of a homeostatic system (blood calcium regulation). Using multidimensional item response theory, we were able to confirm the three-dimensional structure of the theoretical systems-thinking model and to identify the factors causing item difficulty. As hypothesized, indirect relationships and derived inverse conditions are challenging factors for participants in the context of homeostasis across dimensions. Hence, we recommend paying special attention to these factors when teaching homeostasis as part of systems thinking. We assume that allowing students to reason from different initiating conditions in a learning setting may improve their systems-thinking skills.

A Course-Based Undergraduate Research Experience (CURE) in Biology: Developing Systems Thinking through Field Experiences in Restoration Ecology

Course-based undergraduate research experiences (CUREs) introduce research leading to skills acquisition and increased persistence in the major. CUREs generate enthusiasm and interest in doing science and serve as an intervention to increase equity and participation of historically marginalized students. In the second-semester laboratory of our introductory sequence for biology and marine science majors at California State University Monterey Bay (CSUMB), instructors updated and implemented a field-based CURE. The goals of the CURE were to promote increased scientific identity, systems thinking, and equity at a Hispanic-serving institution (HSI). Through the CURE, students engaged in scientific writing through a research paper with a focus on information literacy, critical thinking, and quantitative reasoning as important elements of thinking like a scientist. Course exams also revealed that students showed gains in their ability to evaluate a new biological system using systems thinking. More broadly, because such field-based experiences demonstrate equity gains among Latinx students and a much greater sense of scientific identity, they may have impacts beyond introductory biology including in students' personal and professional lives.

Students' use of chemistry core ideas to explain the structure and stability of DNA

Students tend to think of their science courses as isolated and unrelated to each other, making it difficult for them to see connections across disciplines. In addition, many existing science assessments target rote memorization and algorithmic problem-solving skills. Here, we describe the development, implementation, and evaluation of an activity aimed to help students integrate knowledge across introductory chemistry and biology courses. The activity design and evaluation of students' responses were guided by the Framework for K-12 Science Education as the understanding of core ideas and crosscutting concepts and the development of scientific practices are essential for students at all levels. In this activity, students are asked to use their understanding of noncovalent interactions to explain (a) why the boiling point differs for two pure substances (chemistry phenomenon) and (b) why temperature and base pair composition affects the stability of DNA (biological phenomenon). The activity was implemented at two different institutions (N = 441) in both introductory chemistry and biology courses. Students' overall performance suggests that they can provide sophisticated responses that incorporate their understanding of noncovalent interactions and energy to explain the chemistry phenomenon, but have difficulties integrating the same knowledge to explain the biological phenomenon. Our findings reinforce the notion that students should be provided with opportunities in the classroom to purposefully practice and support the use and integration of knowledge from multiple disciplines. Students' evaluations of the activity indicated that they found it to be interesting and helpful for making connections across disciplines.

Design-Based Research: A Methodology to Extend and Enrich Biology Education Research

Recent calls in biology education research (BER) have recommended that researchers leverage learning theories and methodologies from other disciplines to investigate the mechanisms by which students to develop sophisticated ideas. We suggest design-based research from the learning sciences is a compelling methodology for achieving this aim. Design-based research investigates the "learning ecologies" that move student thinking toward mastery. These "learning ecologies" are grounded in theories of learning, produce measurable changes in student learning, generate design principles that guide the development of instructional tools, and are enacted using extended, iterative teaching experiments. In this essay, we introduce readers to the key elements of design-based research, using our own research into student learning in undergraduate physiology as an example of design-based research in BER. Then, we discuss how design-based research can extend work already done in BER and foster interdisciplinary collaborations among cognitive and learning scientists, biology education researchers, and instructors. We also explore some of the challenges associated with this methodological approach.