Active learning in undergraduate STEM courses boosts student achievement and narrows gaps for underrepresented students compared to traditional lecturing. This meta-analysis aims to further understand the role of active learning practices by interrogating features of the classroom context (e.g., introductory vs. upper-level courses, class size, and discipline) and active learning practices (e.g., type and intensity of active learning) that are correlated with student learning in undergraduate STEM classrooms. After systematically reviewing the literature that was published between 2010 and 2016, and meta-analyzing 134 admitted studies, we found that active learning had a positive impact on student outcomes regardless of class size, course level, or STEM discipline, with an overall effect of roughly half a standard deviation on exam scores (g=0.519, p<0.001, df=231). More importantly, we highlighted two novel results regarding active learning practices. First, student performance was significantly better in courses that employed mid- (g=0.583) or high-intensity (g=0.593) active learning versus lower-intensity (g=0.246), as judged by the amount of class time studies reported students were actively engaged in course activities. Additionally, there was significant heterogeneity in efficacy across different types of active learning employed (QM=120.5, df=7, p<0.001; I2=59.8%). We conclude that most, if not all, types of active learning are effective, and that active learning intensity is associated with stronger effects, although this association may be confounded with other aspects of course redesign. These results suggest that when innovating in their classes, instructors should continually work to increase active learning intensity. Finally, the evidence presented here for active learning’s impact on student outcomes creates a strong foundation for faculty professional development and evaluation.

We updated a recent meta-analysis of active learning’s impact on student achievement in undergraduate STEM courses by following the same protocol to evaluate studies published from 2010-2017. We screened 1659 papers, coded 1294, and found 210 that met five pre-established inclusion criteria and six pre-established criteria for methodological quality. After further dropping 76 studies with no exam scores data, 134 of these studies contained data on student performance on identical or equivalent exams. We found that on average, active learning’s effect size on exam scores was 0.519 ± 0.049, meaning that when students are in active learning classes, they perform roughly half a standard deviation higher on an identical exam. Funnel plots and sensitivity analyses indicated that these results were not due to sampling bias. Active learning had a positive impact on student outcomes regardless of class size, course level, or STEM discipline, though there was heterogeneity in the effects. All of these results are very similar when compared to earlier meta-analyses, however increased resolution in the studies analyzed here revealed two novel results. First, student performance was significantly better in courses that employed high-intensity active learning, defined as students being on task at least two-thirds of class time, versus lower-intensities. Additionally, there was significant heterogeneity in efficacy across different types of active learning employed. These results suggest that most, if not all types of active learning are effective, and that when innovating in their classes, instructors should continually work to increase active learning intensity. We urge caution in interpreting the results on active learning types, however, and propose a preliminary framework for making more-sophisticated and reliable analyses of variation in course design. Finally, the evidence presented here for active learning’s impact on student outcomes creates a strong foundation for faculty professional development and administration. ### Competing Interest Statement The authors have declared no competing interest.

Introductory biology for majors is one of the most consequential courses in STEM, with annual enrollments of several hundred thousand students in the United States alone. To support increased student success and meet current and projected needs for qualified STEM professionals, it will be crucial to redesign majors biology by using explicit learning objectives (LOs) that can be aligned with assessments and active learning exercises. When a course is designed in this way, students have opportunities for the practice and support they need to learn, and instructors can collect the evidence they need to evaluate whether students have mastered key concepts and skills. Following an iterative process of review, revision, and evaluation, which included input from over 800 biology instructors around the country, we produced a nationally endorsed set of lesson-level LOs for a year-long introductory biology for major’s course. These LOs are granular enough to support individual class sessions and provide instructors with a framework for course design that is directly connected to the broad themes in Vision and Change and the general statements in the BioCore and BioSkills Guides. Instructors can implement backward course design by aligning these community endorsed LOs with daily and weekly learning activities and with formative and summative assessments.

Researchers who work on course-based undergraduate research experiences (CUREs) and issues related to science, technology, engineering, and math (STEM) retention have begun exploring changes in student thinking about what it means to be a scientist. To support this effort, we developed rubrics to score answers to three open-response prompts: What does it mean to think like a scientist? What does it mean to do science? and Did you do real research in your coursename labs? The rubric development process was iterative and was based on input from the literature, experienced researchers, and early-career undergraduates. A post hoc analysis showed that the rubric elements map to 27 of 31 statements in the Culture of Scientific Research (CSR) framework, suggesting that scored responses to the three prompts can assess how well students understand what being a science professional entails. Scores on responses from over 400 students who were starting an introductory biology course for majors furnish baseline data from the rubrics and suggest that (i) undergraduates at this level have, as expected, a novice-level understanding of CSR, and (ii) level of understanding in novice students does not vary as a function of demography or academic preparation. Researchers and instructors are encouraged to add CSR to their list of learning objectives for CUREs and consider assessing it using the rubrics provided here.

We developed labs on the evolution of antibiotic resistance to assess the costs and benefits of replacing traditional laboratory exercises in an introductory biology course for majors with a course-based undergraduate research experience (CURE). To assess whether participating in the CURE imposed a cost in terms of exam performance, we implemented a quasi-experiment in which four lab sections in the same term of the same course did the CURE labs, while all other students did traditional labs. To assess whether participating in the CURE impacted other aspects of student learning, we implemented a second quasi-experiment in which all students either did traditional labs over a two-quarter sequence or did CURE labs over a two-quarter sequence. Data from the first experiment showed minimal impact on CURE students' exam scores, while data from the second experiment showed that CURE students demonstrated a better understanding of the culture of scientific research and a more expert-like understanding of evolution by natural selection. We did not find disproportionate costs or benefits for CURE students from groups that are minoritized in science, technology, engineering, and mathematics.

Our current understanding of the factors that influence where birds nest is incomplete, yet such information is important for accurate demographic assessments. To address questions related to spatial distributions of shorebird nests and to evaluate factors that may affect nest distribution in these species, during 2017 and 2019, we studied a small population of semipalmated sandpiper Calidris pusilla breeding in the Central Canadian Arctic, near the Karrak Lake Research Station, in Nunavut. The spatial distribution of semipalmated sandpiper nests at this site suggested loose aggregation, with median nearest neighbor distances of 73.8m and 92.0m in 2017 and 2019, respectively, while no nests were detected on mainland areas in the vicinity. Evidence for the influence of nesting distribution on the daily survival rate of nests, however, was mixed. Neither nearest neighbor distance nor local nest density had a significant effect on daily nest survival in 2017, but in 2019, the best approximating model included an effect of local nest density, which indicated that nests in areas of high density had reduced survival rates. Contrary to other studies assessing settlement and nest site selection in semipalmated sandpipers, the spatial distribution of nests in this population demonstrates aggregation in an otherwise territorial species, but suggests that aggregated nesting can impose a cost on nest survival under certain conditions.

Learning objectives (LOs) are used to communicate the purpose of instruction. Done well, they convey the expectations that the instructor-and by extension, the academic field-has in terms of what students should know and be able to do after completing a course of study. As a result, they help students better understand course activities and increase student performance on assessments. LOs also serve as the foundation of course design, as they help structure classroom practices and define the focus of assessments. Understanding the research can improve and refine instructor and student use of LOs. This essay describes an online, evidence-based teaching guide published by CBE-Life Sciences Education (LSE) at http://lse.ascb.org/learning-objectives. The guide contains condensed summaries of key research findings organized by recommendations for writing and using LOs, summaries of and links to research articles and other resources, and actionable advice in the form of a checklist for instructors. In addition to describing key features of the guide, we also identify areas that warrant further empirical studies.

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.

Thermal data loggers have been used to monitor nest activity for a variety of avian species, primarily by identifying a difference in temperature between the relatively cool environment and the nest, which is warmed by nestlings or attendant adults. Many grassland songbirds, however, nest in warm environments where ambient and nest temperatures are frequently similar, which may limit the ability to identify nesting events from temperature data. Here, we evaluate the efficacy and potential impact of monitoring nests of grassland songbirds with thermal data loggers. We focus on a grassland-obligate species, Botteri's Sparrow (Peucaea botterii), that nests in hot, semiarid grasslands. We located and monitored 225 nests in southeastern Arizona, USA, and placed data loggers below the surface of the nest lining at a subset of 28 nests. To contrast nest temperatures with ambient temperatures, we placed a second data logger in similar vegetation within 3 m of the nest. Data loggers did not affect daily survival rates of nests. We were able to identify the date the nesting attempt ended (i.e., failure or fledging) correctly for all nests based on temperature data recorded during the cool period of the daily temperature cycle when data loggers placed below the nest lining averaged 3.9 degrees C warmer than the environment. During the hot period of the daily cycle, we were able to identify nest cessation correctly for only 46% of nests. Our study demonstrates that thermal data loggers can be used to monitor nest survival of grassland birds successfully provided that ambient temperatures are measurably lower than nest temperatures for at least part of the daily cycle. This provides an alternative to intensive observer-based monitoring that can increase the precision of survival estimates while potentially reducing cost, effort, and risk of disturbance to this group of high conservation concern.

Evolution by natural selection is recognized as both the most important concept in undergraduate biology and the most difficult to teach. Unfortunately, teaching and assessment of evolution have been impaired by legacy approaches that focus on Darwin’s original insights and the Modern Synthesis’ integration of Mendelian genetics, but ignore or downplay advances from what we term the Molecular Synthesis. To create better alignment between instructional approaches and contemporary research in the biosciences, we propose that the primary learning goal in teaching evolution should be for students to connect genotypes, phenotypes, and fitness. To support this approach, we developed and tested assessment questions and scoring rubrics called the Extended Assessing Conceptual Reasoning of Natural Selection (E-ACORNS) instrument. Initial E-ACORNS data suggest that after traditional instruction, few students recognize the molecular synthesis—prompting us to propose that introductory course sequences be re-organized with the molecular synthesis as their central theme.

Students from minoritized groups enter college with interest in STEM but leave these majors at high rates, largely due to inequities in STEM classes. Active learning reduces the disparities in exam scores and passing rates observed in traditional STEM classrooms. Thus, changes in course design can be an important tool in promoting equity in STEM. - submission by Elli Theobald, Scott Freeman

High-structure course designs have reduced achievement gaps for low-income and underrepresented minority students at research universities. But do community college students have time to do the preclass preparation required for intensive active learning, given their work and family commitments? We asked introductory majors biology students at two community colleges, a regional comprehensive university, and a research university (R1) in two states to report the number of hours spent on various activities each week. Our sample included one low-structure and one high-structure course at each institution type. Community college students reported higher levels of nonacademic time commitments than students at the regional comprehensives and the R1s. The community college students in both states reported spending the same amount of time studying for their biology course as the students at the R1s; in one state, the community college students were spending more time studying than the students at the comprehensive university. Our data show that community college students commit as much time to biology as other students, demonstrating that they can readily meet the time demands of a high-structure course. Additional informationNotes on contributorsScott FreemanScott Freeman (srf991@uw.edu) is lecturer emeritus in the Department of Biology at the University of Washington in Seattle, Washington.Pamela Pape-LindstromPamela PapeLindstrom is dean of science, technology, engineering, and mathematics at Harford Community College in Bel Air, Maryland.Anne CasperAnne Casper is professor in the Department of Biology at Eastern Michigan University in Ypsilanti, Michigan.Sarah EddySarah Eddy is assistant professor in biology and the STEM Transformation Institute at Florida International University in Miami, Florida.

Students from underrepresented groups start college with the same level of interest in STEM majors as their peers, but leave STEM at higher rates. We tested the hypothesis that low grades in general chemistry contribute to this "weeding," using records from 25,768 students. In the first course of a general chemistry series, grade gaps based on binary gender, race/ethnicity, socioeconomic status, and family education background ranged from 0.12 to 0.54 on a four-point scale. Gaps persisted when the analysis controlled for academic preparation, indicating that students from underrepresented groups underperformed relative to their capability. Underrepresented students were less likely than well-represented peers to persist in chemistry if they performed below a C-, but more likely to persist if they got a C or better. This "hyperpersistent zone" suggests that reducing achievement gaps could have a disproportionately large impact on efforts to achieve equity in STEM majors and professions.

We tested the hypothesis that underrepresented students in active-learning classrooms experience narrower achievement gaps than underrepresented students in traditional lecturing classrooms, averaged across all science, technology, engineering, and mathematics (STEM) fields and courses. We conducted a comprehensive search for both published and unpublished studies that compared the performance of underrepresented students to their overrepresented classmates in active-learning and traditional-lecturing treatments. This search resulted in data on student examination scores from 15 studies (9,238 total students) and data on student failure rates from 26 studies (44,606 total students). Bayesian regression analyses showed that on average, active learning reduced achievement gaps in examination scores by 33% and narrowed gaps in passing rates by 45%. The reported proportion of time that students spend on in-class activities was important, as only classes that implemented high-intensity active learning narrowed achievement gaps. Sensitivity analyses showed that the conclusions are robust to sampling bias and other issues. To explain the extensive variation in efficacy observed among studies, we propose the heads-and-hearts hypothesis, which holds that meaningful reductions in achievement gaps only occur when course designs combine deliberate practice with inclusive teaching. Our results support calls to replace traditional lecturing with evidence-based, active-learning course designs across the STEM disciplines and suggest that innovations in instructional strategies can increase equity in higher education.

Gender gaps in exam scores or final grades are common in introductory college science and engineering classrooms, with women underperforming relative to men with the same admission test scores or college grade point averages. After failing to close a historically documented gender gap in a large introductory biology course using interventions targeted at training a growth mindset, we implemented interventions designed to reduce student test anxiety. We combined evidence-based exercises based on expressive writing and on reappraising physiological arousal. We also used a valid measure to quantify test anxiety at the start and end of the course. This instrument measures an individual's self-declared or perceived test anxiety-also called trait anxiety-but not the immediate or "state" anxiety experienced during an actual exam. Consistent with previous reports in the literature, we found that women in this population declared much higher test anxiety than men and that students who declared higher test anxiety had lower exam scores than students who declared lower test anxiety. Although the test anxiety interventions had no impact on the level of self-declared trait anxiety, they did significantly increase student exam performance. The treatment benefits occurred in both men and women. These data suggest that 1) a combination of interventions based on expressive writing and reappraising physiological arousal can be a relatively easy manner to boost exam performance in a large-enrollment science, technology, engineering, and mathematics (STEM) course and encourage emotion regulation; 2) women are more willing than men to declare that they are anxious about exams, but men and women may actually experience the same level of anxiety during the exam itself; and 3) women are underperforming in STEM courses for reasons other than gender-based differences in mindset or test anxiety.

Our first two experiments on adapting a high-structure course model to an essentially open-enrollment university produced negative or null results. Our third experiment, however, proved more successful: performance improved for all students, and a large achievement gap that impacted underrepresented minority students under traditional lecturing closed. Although the successful design included preclass preparation videos, intensive active learning in class, and weekly practice exams, student self-report data indicated that total study time decreased. Faculty who have the grit to experiment and persevere in making evidence-driven changes to their teaching can reduce the inequalities induced by economic and educational disadvantage.

Gut microbiota can have important effects on host health, but explanatory factors and pathways that determine gut microbial composition can differ among host lineages. In mammals, host phylogeny is one of the main drivers of gut microbiota, a result of vertical transfer of microbiota during birth. In birds, it is less clear what the drivers might be, but both phylogeny and environmental factors may play a role. We investigated host and environmental factors that underlie variation in gut microbiota composition in eight species of migratory shorebirds. We characterized bacterial communities from 375 fecal samples collected from adults of eight shorebird species captured at a network of nine breeding sites in the Arctic and sub-Arctic ecoregions of North America, by sequencing the V4 region of the bacterial 16S ribosomal RNA gene. Firmicutes (55.4%), Proteobacteria (13.8%), Fusobacteria (10.2%), and Bacteroidetes (8.1%) dominated the gut microbiota of adult shorebirds. Breeding location was the main driver of variation in gut microbiota of breeding shorebirds (R-2 = 11.6%), followed by shorebird host species (R-2 = 1.8%), and sampling year (R-2 = 0.9%), but most variation remained unexplained. Site variation resulted from differences in the core bacterial taxa, whereas rare, lowabundance bacteria drove host species variation. Our study is the first to highlight a greater importance of local environment than phylogeny as a driver of gut microbiota composition in wild, migratory birds under natural conditions.