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Debates in education policy draw on different theories about how to raise children’s achievement. The school competition theory holds that achievement rises when students can choose among competing schools. The school resources theory holds that achievement rises with schools’resources per student. The family resources theory holds that achievement rises as parents become more educated and earn higher incomes. We test all three theories in Chile between 2002 and 2013, when reading and math scores rose by 0.2 to 0.3 standard deviations, as school competition, school resources, and family resources all increased. We compare Chilean municipalities in a difference-in-differences analysis, asking whether test scores rose fastest in municipalities with greater increases in school competition, school resources, or family resources. We find that municipal test scores did not rise with school competition but did rise with family resources (parental education, not income) and, to a smaller extent, with school resources (as measured by class sizes). Results favor the family resource theory, and to a lesser extent the school resource theory, but not the school competition theory.

College students who interact with professors and peers about academic matters have better college outcomes. Although institutional factors influence engagement, prior scholarship has not systematically examined whether class sizes affect students' academic interactions, nor whether race or first-generation status moderate such effects. We conceptualized academic interactions as forms of social capital that are sensitive to institutional characteristics. We analyzed survey data from a random sample of 346 students enrolled at a public research university linked with institutional data on student class size. We employed logistic regression on six dependent variables capturing academic interactions with professors and peers and controlled for precollege characteristics. Compared to students enrolled in smaller classes, students enrolled in larger classes had significantly fewer interactions with professors about course material and with peers about course-related ideas. Social group also moderated some effects of class size. Class size negatively influenced first-generation (but not continuing generation) students' likelihood of talking to professors or TAs about ideas from class. For discussions about future careers, larger classes had profound negative effects on Black students (for interactions with professors) and Latino students (for interactions with peers), but no effect on other groups. We discuss implications for theory and practice.

Environmental conditions and plant size may both alter the outcome of inter-specific plant– plant interactions, with seedlings generally facilitated more strongly than larger individuals in stressful habitats. However, the combined impact of plant size and environmental severity on interactions is poorly understood. Here, we tested explicitly for the first time the hypothesis that ontogenetic shifts in interactions are delayed under increasingly severe conditions by examining the interaction between a grass, Agrostis magellanica, and a cushion plant, Azorella selago, along two severity gradients. The impact of A. selago on A. magellanica abundance, but not reproductive effort, was related to A. magellanica size, with a trend for delayed shifts towards more negative interactions under greater environmental severity. Intermediate-sized individuals were most strongly facilitated, leading to differences in the size-class distribution of A. magellanica on the soil and on A. selago. The A. magellanica size-class distribution was more strongly affected by A. selago than by environmental severity, demonstrating that the plant–plant interaction impacts A. magellanica population structure more strongly than habitat conditions. As ontogenetic shifts in plant–plant interactions cannot be assumed to be constant across severity gradients and may impact species population structure, studies examining the outcome of interactions need to consider the potential for size- or age-related variation in competition and facilitation.

In this study we analyze the temporal variability in the density and the size classes of the Corbicula fluminea (Müller, 1774) at Poxim-Açu River, northeastern Brazil. Densities ranged from 60 ± 103 to 500 ± 240 individual m-², but this variability was not statistically significant. There was no significant relationship between densities and water parameters (depth and flow). The population was mainly composed of young individuals, with 10-14 mm of shell length. Lower densities and predominance of juveniles suggest a recent invasion event. However, C. fluminea was firstly recorded at Poxim-Açu River three years before this study. Thus, these results might reflect a mortality followed by a reinvasion event. A continuous monitoring program is needed to better evaluate whether this population is growing and spreading as well as to determine which environmental variables could be driving the temporal variability of this species.

In tropical rainforests, tree size and number density are influenced by disturbance history, soil, topography, climate, and biological factors that are difficult to predict without detailed and widespread forest inventory data. Here, we quantify tree size–frequency distributions over an old-growth wet tropical forest at the La Selva Biological Station in Costa Rica by using an individual tree crown (ITC) algorithm on airborne lidar measurements. The ITC provided tree height, crown area, the number of trees >10 m height and, predicted tree diameter, and aboveground biomass from field allometry. The number density showed strong agreement with field observations at the plot- (97.4%; 3% bias) and tree-height-classes level (97.4%; 3% bias). The lidar trees size spectra of tree diameter and height closely follow the distributions measured on the ground but showed less agreement with crown area observations. The model to convert lidar-derived tree height and crown area to tree diameter produced unbiased (0.8%) estimates of plot-level basal area and with low uncertainty (6%). Predictions on basal area for tree height classes were also unbiased (1.3%) but with larger uncertainties (22%). The biomass estimates had no significant bias at the plot- and tree-height-classes level (−5.2% and 2.1%). Our ITC method provides a powerful tool for tree- to landscape-level tropical forest inventory and biomass estimation by overcoming the limitations of lidar area-based approaches that require local calibration using a large number of inventory plots.

In an effort to improve the quality of schools, governments around the world have dramatically increased the resources devoted to them. By concentrating on inputs and ignoring the incentives within schools, the resources have yielded little in the way of general improvement in student achievement. This paper provides a review of the US and international evidence on the effectiveness of such input policies. It then contrasts the impact of resources with that of variations in teacher quality that are not systematically related to school resources. Finally, alternative performance incentive policies are described.

Socio‐ecological resilience is the capacity of a system to adapt to changing ecological and social disturbances. Its assessment is extremely important to integrate long‐term management of ecological and social features of natural ecosystems. This is especially true for Sacred Natural Sites, such as sacred forests and groves, where it can reveal the influence of social processes in ecosystem recovery or degradation. Using tree ages determined through dendrochronology and tree population size‐class distributions collected in five sacred forests in Epirus (NW Greece), we explore spatial and temporal dynamics of resilience in a socio‐ecological system, identifying which cultural and social elements characterize resilience in space and time. Our main results show that over past centuries sacred forests in Epirus underwent periods of varying tree establishment rate, depending on the intensity of human activities and historical disturbance events. We also identified strong evidence of the role of the social component (i.e. the church and associated cultural praxis) in determining the spatial extent of the forests' current recovery phase, and thus the overall resilience of the system. Policy implications. Appreciation of the ways sacred forests' ecological resilience is linked to changing socio‐cultural praxis over both temporal and spatial scales is crucial for guiding conservation and restoration strategies. We argue that greater attention should be paid to the role of the social component of socio‐ecological systems and specifically for sacred natural sites that provide both a nucleus of established forest habitat and the conditions necessary for forest recovery and restoration. Read the free Plain Language Summary for this article on the Journal blog. Περίληψη Η κοινωνικο‐οικολογική ανθεκτικότητα είναι η ικανότητα ενός συστήματος να προσαρμόζεται σε μεταβαλλόμενες οικολογικές και κοινωνικές διαταραχές. Η αξιολόγησή της είναι εξαιρετικά σημαντική καθώς ενσωματώνει τη μακροπρόθεσμη διαχείριση οικολογικών και κοινωνικών χαρακτηριστικών των φυσικών οικοσυστημάτων. Αυτό ισχύει ιδιαίτερα για τους Ιερούς Φυσικούς Τόπους, όπως τα ιερά δάση και άλση, όπου μπορεί να αποκαλυφθεί ευκολότερα η επίδραση των κοινωνικών διαδικασιών στην ανάκαμψη ή την υποβάθμιση των συγκεκριμένων οικοσυστημάτων. Χρησιμοποιώντας τις ηλικίες των δέντρων που προσδιορίστηκαν μέσω της δενδροχρονολόγησης και κατανομές κλάσεων του μεγέθους των πληθυσμών τους που συλλέχθηκαν σε πέντε ιερά δάση στην Ήπειρο (ΒΔ Ελλάδα), διερευνούμε τη χωρική και χρονική δυναμική της ανθεκτικότητας σε ένα ιδιαίτερο κοινωνικο‐οικολογικό σύστημα, προσδιορίζοντας ποια πολιτιστικά και κοινωνικά στοιχεία επηρεάζουν την ανθεκτικότητά τους στον χώρο και στον χρόνο. Τα κύρια αποτελέσματά μας δείχνουν ότι κατά τη διάρκεια των τελευταίων αιώνων, τα ιερά δάση στην Ήπειρο πέρασαν περιόδους διαφορετικού ρυθμού εγκατάστασης δέντρων, ανάλογα με την ένταση της ανθρώπινης δραστηριότητας τοπικά, καθώς και ιστορικών συμβάντων διαταραχής αλλά και εγκατάλειψης. Εντοπίσαμε επίσης ισχυρές ενδείξεις για τον ρόλο κοινωνικών παραγόντων (όπως π.χ. της Εκκλησίας, και σχετικών πολιτιστικών πρακτικών) στον καθορισμό της χωρικής έκτασης και της σημερινής φάσης ανάκαμψης του δάσους, και συνεπώς της συνολικής ανθεκτικότητας του συστήματος. Δυνητικές εφαρμογές για τη δασική διαχείριση. Η εκτίμηση των τρόπων σύνδεσης της οικολογικής ανθεκτικότητας των ιερών δασών στις μεταβαλλόμενες κοινωνικο‐πολιτιστικές πρακτικές, τόσο σε χρονική όσο και σε χωρική κλίμακα, είναι ζωτικής σημασίας για τη χάραξη στρατηγικών διατήρησης και αποκατάστασης. Υποστηρίζουμε ότι πρέπει να δοθεί μεγαλύτερη προσοχή στον ρόλο της κοινωνικής συνιστώσας των κοινωνικο‐οικολογικών συστημάτων, ιδιαίτερα για συστήματα όπως οι Ιεροί Φυσικοί Τόποι, που μπορούν να λειτουργήσουν ως πυρήνες εξάπλωσης δασικών ενδιαιτημάτων, αλλά και να προσφέρουν τις απαραίτητες συνθήκες για την ανάκαμψη και αποκατάσταση δασών. Read the free Plain Language Summary for this article on the Journal blog.

This paper examines evidence on the effect of class size on student achievement. First, it is shown that results of quantitative summaries of the literature, such as Hanushek (1997), depend critically on whether studies are accorded equal weight. When studies are given equal weight, resources are systematically related to student achievement. When weights are in proportion to their number of estimates, resources and achievements are not systematically related. Second, a cost-benefit analysis of class size reduction is performed. Results of the Tennessee STAR class-size experiment suggest that the internal rate of return from reducing class size from 22 to 15 students is around 6%.

This study examines the association between class size, teacher characteristics and five non-cognitive student outcomes (i.e., self-control, interpersonal skills, approaches to learning, externalizing and internalizing problem behaviors) in grades K-3. Individual fixed-effects, that control for observed and unobserved time-invariant factors, including student and school time-constant variables, are employed to analyze national data from the Early Childhood Longitudinal Study, Kindergarten Class of 2010–11 (ECLS-K:2011). Results suggest a significant linear association between reducing class size and interpersonal skills. Teacher experience is saliently, positively and significantly related with student self-control, interpersonal skills, and approaches to learning, and negatively associated with externalizing problem behaviors. Teacher education and certification were not associated with any of the five non-cognitive outcomes. Changing schools had a negative effect on student’s self-control.

Problem-based learning (PBL) is an effective and highly efficient teaching approach that is extensively applied in education systems across a variety of countries. This study aimed to investigate the effectiveness of web-based PBL teaching pedagogies in large classes. The cluster sampling method was used to separate two college-level nursing student classes (graduating class of 2013) into two groups. The experimental group (n = 162) was taught using a web-based PBL teaching approach, while the control group (n = 166) was taught using conventional teaching methods. We subsequently assessed the satisfaction of the experimental group in relation to the web-based PBL teaching mode. This assessment was performed following comparison of teaching activity outcomes pertaining to exams and self-learning capacity between the two groups. When compared with the control group, the examination scores and self-learning capabilities were significantly higher in the experimental group (P < 0.01) compared with the control group. In addition, 92.6% of students in the experimental group expressed satisfaction with the new web-based PBL teaching approach. In a large class-size teaching environment, the web-based PBL teaching approach appears to be more optimal than traditional teaching methods. These results demonstrate the effectiveness of web-based teaching technologies in problem-based learning. •Wed-based Problem-based learning is an effective and highly efficient teaching approach.•Practice and effectiveness of the web-based problem-based learning (PBL) teaching mode.•Web-based PBL has better performance than traditional teaching methods.