National and local initiatives focused on the transformation of STEM teaching in higher education have multiplied over the last decade. These initiatives often focus on measuring change in instructional practices, but it is difficult to monitor such change without a national picture of STEM educational practices, especially as characterized by common observational instruments. We characterized a snapshot of this landscape by conducting the first large scale observation-based study. We found that lecturing was prominent throughout the undergraduate STEM curriculum, even in classrooms with infrastructure designed to support active learning, indicating that further work is required to reform STEM education. Additionally, we established that STEM faculty’s instructional practices can vary substantially within a course, invalidating the commonly-used teaching evaluations based on a one-time observation.

A growing body of evidence has shown that active learning has a considerable advantage over traditional lecture for student learning in undergraduate STEM classes, but there have been few large-scale studies to identify the specific types of activities that have the greatest impact on learning. We therefore undertook a large-scale, curriculum-wide study to investigate the effects of time spent on a variety of classroom activities on learning gains. We quantified classroom practices and related these to student learning, assessed using diagnostic tests written by over 3700 students, across 31 undergraduate biology classes at a research-intensive university in the Pacific Northwest. The most significant positive predictor of learning gains was the use of group work, supporting the findings of previous studies. Strikingly, we found that the addition of worksheets as an active learning tool for in-class group activities had the strongest impact on diagnostic test scores. This particular low-tech activity promotes student collaboration, develops problem solving skills, and can be used to inform the instructor about what students are struggling with, thus providing opportunities for valuable and timely feedback. Overall, our results indicate that group activities with low barriers to entry, such as worksheets, can result in significant learning gains in undergraduate science.

No abstract

SUMMARYModels of branchial transport in teleosts have been reshaped by the recent discovery of Rhesus (Rh) glycoproteins, a family of proteins that facilitate the movement of NH 3 across cell membranes. This study examines the effects of crowding and feeding on ammonia excretion in gulf toadfish (Opsanus beta) within the context of Rh glycoproteins and the ammonia-fixing enzyme, glutamine synthetase (GS). Four Rh isoforms (Rhag, Rhbg, Rhcg1 and Rhcg2) were isolated from toadfish. Tissue distributions showed higher levels of mRNA expression in the gills and liver, moderate levels in the intestine and lower levels in the stomach. Crowding significantly lowered branchial Rh expression and ammonia excretion rates in fasted toadfish. A comparison of Rh expression in the digestive tract revealed relatively low levels of Rhcg1 and Rhcg2 in the stomach and high mRNA abundance of Rhbg, Rhcg1 and Rhcg2 in the intestine of fasted, crowded toadfish. We speculate that these trends may reduce secretion and enhance absorption, respectively, to minimize the amount of ammonia that is lost through gastrointestinal routes. By contrast, these patterns of expression were modified in response to an exogenous ammonia load via feeding. Post-prandial ammonia excretion rates were elevated twofold, paralleled by similar increases in branchial Rhcg1 mRNA, gastric Rhcg1 mRNA and mRNA of all intestinal Rh isoforms. These changes were interpreted as an attempt to increase post-prandial ammonia excretion rates into the environment owing to a gradient created by elevated circulating ammonia concentrations and acidification of the digestive tract. Overall, we provide evidence that toadfish modulate both the expression of Rh isoforms and urea synthesis pathways to tightly control and regulate nitrogen excretion. Supplementary material available online at

SUMMARYGulf toadfish, Opsanus beta, are one among a group of unusual teleosts that excrete urea as their predominant nitrogen end product in response to stressful conditions. Under conditions of crowding or confinement, fasted toadfish excrete the majority of their nitrogen waste in large pulses of urea (>90% of total nitrogen) lasting up to 3 h. An earlier study demonstrated that cortisol has an inhibitory influence on urea pulse size. The present study tested the hypothesis that cortisol mediates changes in urea pulse size in ureotelic toadfish through the glucocorticoid receptor (GR) and not the mineralocorticoid receptor (MR). In vivo pharmacological investigations were used to manipulate the corticosteroid system in crowded toadfish, including experimentally lowering plasma cortisol levels by the injection of metyrapone, blocking cortisol receptors through exposure to either RU-486 (GR antagonist) and spironolactone (MR antagonist), or through exogenous infusion of the tetrapod mineralocorticoid aldosterone (tetrapod MR agonist). The data demonstrate that lowering the activity of cortisol, either by inhibiting its synthesis or by blocking its receptor, resulted in a two-to threefold increase in pulse size with no accompanying change in pulse frequency. Treatment with spironolactone elicited a minor (~1.5-fold) reduction in pulse size, as did aldosterone treatment, suggesting that the antimineralocorticoid spironolactone has an agonistic effect in a piscine system. In summary, the evidence suggests that urea transport mechanisms in pulsing toadfish are upregulated in response to low cortisol, mediated primarily by GRs, and to a lesser extent MRs.