Introductory biology students' conceptual models and explanations of the origin of variation

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.

Developing Student Expertise in Evolution: Cognitive Construals Complement Key Concepts in Student Representations

Genetic variation is historically challenging for undergraduate students to master, potentially due to its grounding in both evolution and genetics. Traditionally, student expertise in genetic variation has been evaluated using Key Concepts. However, Cognitive Construals may add to a more nuanced picture of students' developing expertise. Here, we analyze the occurrence of Key Concepts and Cognitive Construals among three types of student representations: interviews, drawn models, and constructed responses (CRs). Our mixed-methods analysis indicates that differential survival and differential reproduction occur more often in interviews than in CRs. In our interviews, presence of Cognitive Construals indicate varying levels of understanding of genetic variation, but we were not able to detect Cognitive Construals in students' models or CRs. Finally, our analyses of both Key Concepts and Cognitive Construals in student representations indicate that Cognitive Construals can co-occur with any number of Key Concepts, and that the presence of Construal-based language alone does not seem to correlate to the expert nature of a response. Taken together, our results highlight the need for instructors to avoid treating Construal-based language as implicit disconnects in student understanding, and to use multiple methods to gain a holistic picture of student expertise.

Modeling in molecular genetics allows students to make connections between biological scales

Students often see college courses as the presentation of disconnected facts, especially in the life sciences. Student-created Structure Mechanism/Relationship Function (SMRF) models were analyzed to understand students' abilities to make connections between genotype, phenotype, and evolution. Students were divided into two sections; one section received instructions that included a specific gene as an example related to larger issues like human disease or the environment. The other section was only given generic examples, like gene X and phenotype Y. Coding of exam models and a comprehensive (extensive) model reveled students were able to make links and work within and between biological scales of organization. Modeling provided a way to show and allow students to practice and demonstrate the ability to build step-by-step causal relationships that link ideas together. We also observed a small differing with students receiving the specific prompt performing better than students receiving generic prompt at the point in the semester where linking across many biological scales was required to be successful.

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.

Students explain evolution by natural selection differently for humans versus nonhuman animals

Evolution is foundational to understanding biology, yet learners at all stages have incomplete and incorrect ideas that persist beyond graduation. Contextual features of prompts (e.g., taxon of organism, acquisition vs. loss of traits, etc.) have been shown to influence both the learning process and the ideas students express in explanations of evolutionary processes. In this study, we compare students' explanations of natural selection for humans versus a nonhuman animal (cheetah) at different times during biology instruction. We found "taxon" to be a significant predictor of the content of students' explanations. Responses to "cheetah" prompts contained a larger number and diversity of key concepts (e.g., variation, heritability, differential reproduction) and fewer naïve ideas (e.g., need, adapt) when compared with responses to an isomorphic prompt containing "human" as the organism. Overall, instruction increased the prevalence of key concepts, reduced naïve ideas, and caused a modest reduction in differences due to taxon. Our findings suggest that the students are reasoning differently about evolutionary processes in humans as compared with nonhuman animals, and that targeted instruction may both increase students' facility with key concepts while reducing their susceptibility to contextual influences.

Assessing how well students understand the molecular basis of evolution by natural selection

Researchers have called for undergraduate courses to update teaching frameworks based on the Modern Synthesis with insights from molecular biology, by stressing the molecular underpinnings of variation and adaptation. To support this goal, we developed a modified version of the widely used Assessing Conceptual Reasoning of Natural Selection (ACORNS) instrument. The expanded tool, called the E-ACORNS, is explicitly designed to test student understanding of the connections among genotypes, phenotypes, and fitness. E-ACORNS comprises a slight modification to the ACORNS open-response prompts and a new scoring rubric. The rubric is based on five core concepts in evolution by natural selection, with each concept broken into elements at the novice, intermediate, and expert-level understanding. Initial tests of the E-ACORNS showed that (1) upper-level undergraduates can score responses reliably and quickly, and (2) students who were just starting an introductory biology series for majors do not yet grasp the molecular basis of phenotypic variation and its connection to fitness.

Using Systems and Systems Thinking to Unify Biology Education

As biological science rapidly generates new knowledge and novel approaches to address increasingly complex and integrative questions, biology educators face the challenge of teaching the next generation of biologists and citizens the skills and knowledge to enable them to keep pace with a dynamic field. Fundamentally, biology is the science of living systems. Not surprisingly, systems is a theme that pervades national reports on biology education reform. In this essay, we present systems as a unifying paradigm that provides a conceptual framework for all of biology and a way of thinking that connects and integrates concepts with practices. To translate the systems paradigm into concrete outcomes to support instruction and assessment in the classroom, we introduce the biology systems-thinking (BST) framework, which describes four levels of systems-thinking skills: 1) describing a system's structure and organization, 2) reasoning about relationships within the system, 3) reasoning about the system as a whole, and 4) analyzing how a system interacts with other systems. We conclude with a series of questions aimed at furthering conversations among biologists, biology education researchers, and biology instructors in the hopes of building support for the systems paradigm.

Improving Students' Understanding of Biological Variation in Experimental Design and Analysis through a Short Model-Based Curricular Intervention

When conducting biological investigations, experts constantly integrate their conceptual and quantitative understanding of variation with the design and analysis of the investigation. This process is difficult for students, because curricula often treat these concepts as separate components. This study describes the effect of a curricular intervention aimed at improving students' conceptual and quantitative understanding of variation in the context of experimental design and analysis. A model-based intervention curriculum consisting of five short modules was implemented in an introductory biology laboratory course. All students received the regular laboratory curriculum, and half of the students also received the Intervention curriculum. Students' understanding of variation was assessed using a published 16-question multiple-choice instrument designed and validated by the research team. Students were assessed before and after the intervention was implemented, and normalized gain scores were calculated. Students who received the intervention showed significantly higher normalized gains than students who did not receive the intervention. This effect was not influenced by students' gender or exposure to prior statistics courses and persisted into and through the following semester's laboratory course. These results provide support for the use of model-based approaches to improve students' understanding of biological variation in experimental design and analysis.

Supporting Scientific Practice through Model-Based Inquiry: A Students'-Eye View of Grappling with Data, Uncertainty, and Community in a Laboratory Experience

Modeling is a scientific practice that supports creative reasoning, motivates inquiry, and facilitates community sense-making. This paper explores students' perspectives on modeling in an undergraduate laboratory course, Authentic Inquiry through Modeling (AIM-Bio), in which they proposed, tested, and revised their own models. We conducted comparative case studies of eight students over a semester. Students described using models to support multiple forms of scientific reasoning and hypothesis generation. They recounted the challenges of dealing with uncertainty and integrating diverse ideas. They also described how these challenges pushed their thinking. Overall, students reported feeling a sense of scientific authenticity and agency through their modeling experience. We additionally provide an in-depth look at two students whose unique experiences in AIM-Bio emphasize the variable ways modeling can support inquiry learning. We claim that modeling emerged as a legitimate practice among students, because the AIM-Bio curriculum encouraged diversity in students' models, provided opportunities for students to grapple with uncertainty, and fostered collaboration between students. We suggest that biology educators consider how model-based inquiry can allow students to participate in science, as a way to support interest in, identification with, and ultimately persistence in science, technology, engineering, and mathematics fields.

BioSkills Guide: Development and National Validation of a Tool for Interpreting the Vision and Change Core Competencies

To excel in modern science, technology, engineering, and mathematics careers, biology majors need a range of transferable skills, yet competency development is often a relatively underdeveloped facet of the undergraduate curriculum. We have elaborated the Vision and Change core competency framework into a resource called the BioSkills Guide, a set of measurable learning outcomes that can be more readily implemented by faculty. Following an iterative review process including more than 200 educators, we gathered evidence of the BioSkills Guide's content validity using a national survey of more than 400 educators. Rates of respondent support were high (74.3-99.6%) across the 77 outcomes in the final draft. Our national sample during the development and validation phases included college biology educators representing more than 250 institutions, including 73 community colleges, and a range of course levels and biology subdisciplines. Comparison of the BioSkills Guide with other science competency frameworks reveals significant overlap but some gaps and ambiguities. These differences may reflect areas where understandings of competencies are still evolving in the undergraduate biology community, warranting future research. We envision the BioSkills Guide supporting a variety of applications in undergraduate biology, including backward design of individual lessons and courses, competency assessment development, and curriculum mapping and planning.

Scaffolding Activities Increase Performance and Lower Frustration with Genotype-to-Evolution Models in Molecular Genetics

Conceptual modeling was introduced in molecular genetics so students could integrate topics and apply molecular reasoning and mechanisms to phenotype, inheritance, and population dynamics. Structure Mechanism Relationship Function (SMRF) models were introduced. SMRF models focus on the function of a specified system using structures/nouns in boxes and processes/relationships/verbs on arrows. This SMRF model formatting enables discussion, feedback, and assessment.  Scaffolding activities were introduced to provide students with support for modeling and were intended to decrease or prevent students’ frustration, intimidation, and discouragement during the learning process.  Comparing a semester without scaffolding activities to semesters with scaffolding results indicate the following benefits: 1) better performance on modeling on first exam, 2) less student resistance towards modeling, and 3) better use of class time.  This article has the training activity for SMRF modeling, scaffolding activities, a grading rubric, and selection of adaptable question prompts to make conceptual modeling more accessible to instructors.

Development of the Biological Variation In Experimental Design And Analysis (BioVEDA) assessment

Variation is an important concept that underlies experimental design and data analysis. Incomplete understanding of variation can preclude students from designing experiments that adequately manage organismal and experimental variation, and from accurately conducting and interpreting statistical analyses of data. Because of the lack of assessment instruments that measure students' ideas about variation in the context of biological investigations, we developed the Biological Variation in Experimental Design and Analysis (BioVEDA) assessment. Psychometric analyses indicate that BioVEDA assessment scores are reliable/precise. We provide evidence that the BioVEDA instrument can be used to evaluate students' understanding of biological variation in the context of experimental design and analysis relative to other students and to their prior scores.

Use of Mobile Technologies in Personal Learning Environments of Intercultural Contexts: Individual and Group Tasks

This paper presents the results of the analysis of the personal learning environments (PLE) used individually and in groups by fifth grade primary education students. The main objective was to determine if the use of mobile technologies in the students’ PLEs encouraged their school integration and learning in intercultural communities. For this, a content analysis of the students’ responses to an ad hoc interview was carried out, with a content validity index of 0.89. The students represented their answers using 41 concept maps in the individual tasks and 5 in the group tasks, which were analyzed with the Nvivo software in its latest version. The results show the categorization of the students’ responses in three dimensions: read, make/reflection and relationship. Among the main conclusions, it was obtained that, in both types of tasks, the strategies and tools that fostered intercultural relationships, intercultural education and communication between the students, and therefore school integration, are mostly linked to the use of mobile technologies applications, such as Wikipedia, the internet, Word, PowerPoint, social networks and YouTube, although it is essential to develop more studies to have more data to understand the phenomenon in depth.

Meeting the Needs of A Changing Landscape: Advances and Challenges in Undergraduate Biology Education

Over the last 25 years, reforms in undergraduate biology education have transformed the way biology is taught at many institutions of higher education. This has been fueled in part by a burgeoning discipline-based education research community, which has advocated for evidence-based instructional practices based on findings from research. This perspective will review some of the changes to undergraduate biology education that have gained or are currently gaining momentum, becoming increasingly common in undergraduate biology classrooms. However, there are still areas in need of improvement. Although more underrepresented minority students are enrolling in and graduating from biology programs than in the past, there is a need to understand the experiences and broaden participation of other underserved groups in biology and ensure biology classroom learning environments are inclusive. Additionally, although understanding biology relies on understanding concepts from the physical sciences and mathematics, students still rarely connect the concepts they learn from other STEM disciplines to biology. Integrating concepts and practices across the STEM disciplines will be critical for biology graduates as they tackle the biological problems of the twenty-first century.

Exploring Students' Descriptions of Mutation from a Cognitive Perspective Suggests How to Modify Instructional Approaches

Prior studies have shown that students have difficulty understanding the role of mutation in evolution and genetics. However, little is known about unifying themes underlying students' difficulty with mutation. In this study, we examined students' written explanations about mutation from a cognitive science perspective. According to one cognitive perspective, scientific phenomena can be perceived as entities or processes, and the miscategorization of processes as entities can lead to noncanonical ideas about scientific phenomena that are difficult to change. Students' incorrect categorization of processes as entities is well documented in physics but has not been studied in biology. Unlike other scientific phenomena that have been studied, the word "mutation" refers to both the process causing a change in the DNA and the entity, the altered DNA, making mutation a relevant concept for exploration and extension of this theory. In this study, we show that, even after instruction on mutation, the majority of students provided entity-focused descriptions of mutation in response to a question that prompted for a process-focused description in a lizard or a bacterial population. Students' noncanonical ideas about mutation occurred in both entity- and process-focused descriptions. Implications for conceptual understanding and instruction are discussed.

Biological Variation as a Threshold Concept: Can We Measure Threshold Crossing?

Threshold concepts are fundamental to a discipline and, once understood, transform students' understanding and perception of the subject. Despite the value of threshold concepts as a learning "portal" for heuristic purposes, there is limited empirical evidence of threshold crossing or achieving mastery. As a threshold concept, biological variation within species is fundamental to understanding evolution and provides a target for analyzing threshold crossing. We aimed to 1) examine student understanding of variation using four dimensions of a threshold concept (discursive, troublesome, liminal, and integrative), 2) measure "threshold crossing," and 3) investigate the utility of the threshold concept framework to curriculum design. We conducted semistructured interviews of 29 students affiliated with a "variation-enriched" curriculum in a cross-sectional design with precurriculum, current, and postcurriculum groups (Pre, Current, and Post) and an outgroup of three postbaccalaureate advanced learners (Outgroup). Interview transcripts revealed that Current students expand their "variation discourse," while the Post group and Outgroup displayed conformity in word choice about variation. The Post and Current groups displayed less troublesome and more integrative responses. Pre, Post, and Outgroup explanations' revealed liminality, with discomfort and uncertainty regardless of accuracy. When we combined all four threshold concept dimensions for each respondent, patterns indicative of threshold crossing emerged along with new insight regarding curricular design.

Authentic Inquiry through Modeling in Biology (AIM-Bio): An Introductory Laboratory Curriculum That Increases Undergraduates' Scientific Agency and Skills

Providing opportunities for science, technology, engineering, and mathematics undergraduates to engage in authentic scientific practices is likely to influence their view of science and may impact their decision to persist through graduation. Laboratory courses provide a natural place to introduce students to scientific practices, but existing curricula often miss this opportunity by focusing on confirming science content rather than exploring authentic questions. Integrating authentic science within laboratory courses is particularly challenging at high-enrollment institutions and community colleges, where access to research-active faculty may be limiting. The Authentic Inquiry through Modeling in Biology (AIM-Bio) curriculum presented here engages students in authentic scientific practices through iterative cycles of model generation, testing, and revision. AIM-Bio university and community college students demonstrated their ability to propose diverse models for biological phenomena, formulate and address hypotheses by designing and conducting experiments, and collaborate with classmates to revise models based on experimental data. Assessments demonstrated that AIM-Bio students had an enhanced sense of project ownership and greater identification as scientists compared with students in existing laboratory courses. AIM-Bio students also experienced measurable gains in their nature of science understanding and skills for doing science. Our results suggest AIM-Bio as a potential alternative to more resource-intensive curricula with similar outcomes.

Connecting Structure-Property and Structure-Function Relationships across the Disciplines of Chemistry and Biology: Exploring Student Perceptions

While many university students take science courses in multiple disciplines, little is known about how they perceive common concepts from different disciplinary perspectives. Structure-property and structure-function relationships have long been considered important explanatory concepts in the disciplines of chemistry and biology, respectively. Fourteen university students concurrently enrolled in introductory chemistry and biology courses were interviewed to explore their perceptions regarding 1) the meaning of structure, properties, and function; 2) the presentation of these concepts in their courses; and 3) how these concepts might be related. Findings suggest that the concepts of structure and properties were interpreted similarly between chemistry and biology, but students more closely associated the discussion of structure-property relationships with their chemistry courses and structure-function with biology. Despite receiving little in the way of instructional support, nine students proposed a coherent conceptual relationship, indicating that structure determines properties, which determine function. Furthermore, students described ways in which they connected and benefited from their understanding. Though many students are prepared to make these connections, we would encourage instructors to engage in cross-disciplinary conversations to understand the shared goals and disciplinary distinctions regarding these important concepts in an effort to better support students unable to construct these connections for themselves.

Further Effects of Phylogenetic Tree Style on Student Comprehension in an Introductory Biology Course

Phylogenetic trees have become increasingly important across the life sciences, and as a result, learning to interpret and reason from these diagrams is now an essential component of biology education. Unfortunately, students often struggle to understand phylogenetic trees. Style (i.e., diagonal or bracket) is one factor that has been observed to impact how students interpret phylogenetic trees, and one goal of this research was to investigate these style effects across an introductory biology course. In addition, we investigated the impact of instruction that integrated diagonal and bracket phylogenetic trees equally. Before instruction, students were significantly more accurate with the bracket style for a variety of interpretation and construction tasks. After instruction, however, students were significantly more accurate only for construction tasks and interpretations involving taxa relatedness when using the bracket style. Thus, instruction that used both styles equally mitigated some, but not all, style effects. These results inform the development of research-based instruction that best supports student understanding of phylogenetic trees.

Effectiveness and Adoption of a Drawing-to-Learn Study Tool for Recall and Problem Solving: Minute Sketches with Folded Lists

Drawing by learners can be an effective way to develop memory and generate visual models for higher-order skills in biology, but students are often reluctant to adopt drawing as a study method. We designed a nonclassroom intervention that instructed introductory biology college students in a drawing method, minute sketches in folded lists (MSFL), and allowed them to self-assess their recall and problem solving, first in a simple recall task involving non-European alphabets and later using unfamiliar biology content. In two preliminary ex situ experiments, students had greater recall on the simple learning task, non-European alphabets with associated phonetic sounds, using MSFL in comparison with a preferred method, visual review (VR). In the intervention, students studying using MSFL and VR had ∼50-80% greater recall of content studied with MSFL and, in a subset of trials, better performance on problem-solving tasks on biology content. Eight months after beginning the intervention, participants had shifted self-reported use of drawing from 2% to 20% of study time. For a small subset of participants, MSFL had become a preferred study method, and 70% of participants reported continued use of MSFL. This brief, low-cost intervention resulted in enduring changes in study behavior.

University Students' Conceptual Knowledge of Randomness and Probability in the Contexts of Evolution and Mathematics

Students of all ages face severe conceptual difficulties regarding key aspects of evolution-the central, unifying, and overarching theme in biology. Aspects strongly related to abstract "threshold" concepts like randomness and probability appear to pose particular difficulties. A further problem is the lack of an appropriate instrument for assessing students' conceptual knowledge of randomness and probability in the context of evolution. To address this problem, we have developed two instruments, Randomness and Probability Test in the Context of Evolution (RaProEvo) and Randomness and Probability Test in the Context of Mathematics (RaProMath), that include both multiple-choice and free-response items. The instruments were administered to 140 university students in Germany, then the Rasch partial-credit model was applied to assess them. The results indicate that the instruments generate reliable and valid inferences about students' conceptual knowledge of randomness and probability in the two contexts (which are separable competencies). Furthermore, RaProEvo detected significant differences in knowledge of randomness and probability, as well as evolutionary theory, between biology majors and preservice biology teachers.

Investigating Undergraduate Students' Use of Intuitive Reasoning and Evolutionary Knowledge in Explanations of Antibiotic Resistance

Natural selection is a central concept throughout biology; however, it is a process frequently misunderstood. Bacterial resistance to antibiotic medications provides a contextual example of the relevance of evolutionary theory and is also commonly misunderstood. While research has shed light on student misconceptions of natural selection, minimal study has focused on misconceptions of antibiotic resistance. Additionally, research has focused on the degree to which misconceptions may be based in the complexity of biological information or in pedagogical choices, rather than in deep-seated cognitive patterns. Cognitive psychology research has established that humans develop early intuitive assumptions to make sense of the world. In this study, we used a written assessment tool to investigate undergraduate students' misconceptions of antibiotic resistance, use of intuitive reasoning, and application of evolutionary knowledge to antibiotic resistance. We found a majority of students produced and agreed with misconceptions, and intuitive reasoning was present in nearly all students' written explanations. Acceptance of a misconception was significantly associated with production of a hypothesized form of intuitive thinking (all p ≤ 0.05). Intuitive reasoning may represent a subtle but innately appealing linguistic shorthand, and instructor awareness of intuitive reasoning's relation to student misunderstandings has potential for addressing persistent misconceptions.

Beyond the Central Dogma: Model-Based Learning of How Genes Determine Phenotypes

In an introductory biology course, we implemented a learner-centered, model-based pedagogy that frequently engaged students in building conceptual models to explain how genes determine phenotypes. Model-building tasks were incorporated within case studies and aimed at eliciting students' understanding of 1) the origin of variation in a population and 2) how genes/alleles determine phenotypes. Guided by theory on hierarchical development of systems-thinking skills, we scaffolded instruction and assessment so that students would first focus on articulating isolated relationships between pairs of molecular genetics structures and then integrate these relationships into an explanatory network. We analyzed models students generated on two exams to assess whether students' learning of molecular genetics progressed along the theoretical hierarchical sequence of systems-thinking skills acquisition. With repeated practice, peer discussion, and instructor feedback over the course of the semester, students' models became more accurate, better contextualized, and more meaningful. At the end of the semester, however, more than 25% of students still struggled to describe phenotype as an output of protein function. We therefore recommend that 1) practices like modeling, which require connecting genes to phenotypes; and 2) well-developed case studies highlighting proteins and their functions, take center stage in molecular genetics instruction.

Scientific Process Flowchart Assessment (SPFA): A Method for Evaluating Changes in Understanding and Visualization of the Scientific Process in a Multidisciplinary Student Population

The scientific process is nonlinear, unpredictable, and ongoing. Assessing the nature of science is difficult with methods that rely on Likert-scale or multiple-choice questions. This study evaluated conceptions about the scientific process using student-created visual representations that we term "flowcharts." The methodology, Scientific Process Flowchart Assessment (SPFA), consisted of a prompt and rubric that was designed to assess students' understanding of the scientific process. Forty flowcharts representing a multidisciplinary group without intervention and 26 flowcharts representing pre- and postinstruction were evaluated over five dimensions: connections, experimental design, reasons for doing science, nature of science, and interconnectivity. Pre to post flowcharts showed a statistically significant improvement in the number of items and ratings for the dimensions. Comparison of the terms used and connections between terms on student flowcharts revealed an enhanced and more nuanced understanding of the scientific process, especially in the areas of application to society and communication within the scientific community. We propose that SPFA can be used in a variety of circumstances, including in the determination of what curricula or interventions would be useful in a course or program, in the assessment of curriculum, or in the evaluation of students performing research projects.

Exploring the MACH Model's Potential as a Metacognitive Tool to Help Undergraduate Students Monitor Their Explanations of Biological Mechanisms

When undergraduate biology students learn to explain biological mechanisms, they face many challenges and may overestimate their understanding of living systems. Previously, we developed the MACH model of four components used by expert biologists to explain mechanisms: Methods, Analogies, Context, and How. This study explores the implementation of the model in an undergraduate biology classroom as an educational tool to address some of the known challenges. To find out how well students' written explanations represent components of the MACH model before and after they were taught about it and why students think the MACH model was useful, we conducted an exploratory multiple case study with four interview participants. We characterize how two students explained biological mechanisms before and after a teaching intervention that used the MACH components. Inductive analysis of written explanations and interviews showed that MACH acted as an effective metacognitive tool for all four students by helping them to monitor their understanding, communicate explanations, and identify explanatory gaps. Further research, though, is needed to more fully substantiate the general usefulness of MACH for promoting students' metacognition about their understanding of biological mechanisms.