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Lecture is prominent, but practices vary A large body of evidence demonstrates that strategies that promote student interactions and cognitively engage students with content ( 1 ) lead to gains in learning and attitudinal outcomes for students in science, technology, engineering, and mathematics (STEM) courses ( 1 , 2 ). Many educational and governmental bodies have called for and supported adoption of these student-centered strategies throughout the undergraduate STEM curriculum. But to the extent that we have pictures of the STEM undergraduate instructional landscape, it has mostly been provided through self-report surveys of faculty members, within a particular STEM discipline [e.g., ( 3 – 6 )]. Such surveys are prone to reliability threats and can underestimate the complexity of classroom environments, and few are implemented nationally to provide valid and reliable data ( 7 ). Reflecting the limited state of these data, a report from the U.S. National Academies of Sciences, Engineering, and Medicine called for improved data collection to understand the use of evidence-based instructional practices ( 8 ). We report here a major step toward a characterization of STEM teaching practices in North American universities based on classroom observations from over 2000 classes taught by more than 500 STEM faculty members across 25 institutions.

Cellulose biosynthesis in plant secondary cell walls forms the basis of vascular development in land plants, with xylem tissues constituting the vast majority of terrestrial biomass. We used plant lines that contained an inducible master transcription factor controlling xylem cell fate to quantitatively image fluorescently tagged cellulose synthase enzymes during cellulose deposition in living protoxylem cells. The formation of secondary cell wall thickenings was associated with a redistribution and enrichment of CESA7-containing cellulose synthase complexes (CSCs) into narrow membrane domains. The velocities of secondary cell wall–specific CSCs were faster than those of primary cell wall CSCs during abundant cellulose production. Dynamic intracellular trafficking of endomembranes in combination with increased velocity and high density of CSCs, enables cellulose to be synthesized rapidly in secondary cell walls.

Opportunity to learn (OTL) is rare among the many concepts that education researchers use to depict the complexity of the schooling process. Although designed as a technical concept to ensure valid cross-national comparisons, OTL has changed how researchers, educators, and policymakers think about the determinants of student learning. This article examines the evolution of OTL from a research concept to a policy instrument. It describes OTL’s intellectual origins in the IEA studies and the role of OTL research in education indicator development. The article then outlines OTL’s emergence as a potential policy tool, and assesses its political and technical feasibility.

Policymakers continue to view student assessment as an appealing instrument of education policy, and they have found a wider variety of uses for it over the past two decades. This article explores the policy uses of assessment, focusing particularly on its persuasive role in encouraging higher levels of educational performance and on its accountability and regulatory functions. The purpose is to provide a framework that will help explain the reasoning of policymakers who continue to insist that assessments can be used for multiple purposes, even in light of their own prior experience and expert evidence to the contrary.

As the number of local institutions that train individuals for employment has grown, policymakers have become concerned about possible duplication and wasteful competition. Potential solutions to this perceived problem typically revolve around strategies for encouraging greater coordination among local education and training agencies. Yet little is known about either the extent of duplication in local communities or about interactions among institutions. To begin to fill this gap, we conducted comparative case studies of eight communities. We found little service overlap or competition. Instead, using a variety of mechanisms, local institutions have established clear divisions of labor and have linked themselves in well-defined, though largely informal, systems. The present study concludes with a discussion of how state and federal policy might facilitate the creation and maintenance of effective local systems of work-related education and training.

M. STEPHEN WEATHERFORD and LORRAINE M. MCDONNELL review the formulation and congressional conflict over President Clinton's economic program during the new administration's first year. They argue that the success of presidential initiatives cannot be adequately evaluated without considering changes in national politics over the last two decades, particularly the increasing independence of legislative and executive branches and the growing combativeness of parties.

In the 1960s, survival for the NEA required the delivery of status and economic benefits to classroom teachers through collective bargaining. Now, recognizing the limits of bargaining, NEA leaders are turning to political action. How successful this strategy will be is still an open question.

While numerous epidemiologic studies have found an association between higher serum 25-hydroxyvitamin D [25(OH)D] concentrations and lower breast cancer risk, few have assessed this association for concentrations >40 ng/ml. To investigate the relationship between 25(OH)D concentration and breast cancer risk across a broad range of 25(OH)D concentrations among women aged 55 years and older. Analyses used pooled data from two randomized clinical trials (N = 1129, N = 2196) and a prospective cohort (N = 1713) to examine a broad range of 25(OH)D concentrations. The outcome was diagnosis of breast cancer during the observation periods (median: 4.0 years). Three analyses were conducted: 1) Incidence rates were compared according to 25(OH)D concentration from <20 to ≥60 ng/ml (<50 to ≥150 nmol/L), 2) Kaplan-Meier plots were developed and 3) multivariate Cox regression was used to examine the association between 25(OH)D and breast cancer risk using multiple 25(OH)D measurements. Within the pooled cohort (N = 5038), 77 women were diagnosed with breast cancer (age-adjusted incidence: 512 cases per 100,000 person-years). Results were similar for the three analyses. First, comparing incidence rates, there was an 82% lower incidence rate of breast cancer for women with 25(OH)D concentrations ≥60 vs <20 ng/ml (Rate Ratio = 0.18, P = 0.006). Second, Kaplan-Meier curves for concentrations of <20, 20-39, 40-59 and ≥60 ng/ml were significantly different (P = 0.02), with the highest proportion breast cancer-free in the ≥60 ng/ml group (99.3%) and the lowest proportion breast cancer-free in the <20 ng/ml group (96.8%). The proportion with breast cancer was 78% lower for ≥60 vs <20 ng/ml (P = 0.02). Third, multivariate Cox regression revealed that women with 25(OH)D concentrations ≥60 ng/ml had an 80% lower risk of breast cancer than women with concentrations <20 ng/ml (HR = 0.20, P = 0.03), adjusting for age, BMI, smoking status, calcium supplement intake, and study of origin. Higher 25(OH)D concentrations were associated with a dose-response decrease in breast cancer risk with concentrations ≥60 ng/ml being most protective.