2,687 research outputs found

    “I had never really made sense of that before”: Constructing Mathematical Content Knowledge and Teaching through Story Telling

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    How do teacher educators in two different fields help pre-service teachers bridge content and pedagogical knowledge? This paper explores the experience of using story-telling over two courses that are required in an early childhood teacher education program. The authors, from two different colleges, used reflection prompted by story-telling to collaboratively support the construction of content knowledge in both a math content class and in a math methods class. Students were able to reflect on their own math content knowledge by telling and retelling their understanding of math knowledge construction and that of children they worked with over the semester

    Silicon materials task of the low cost solar array project, part 2

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    Purity requirements for solar cell grade silicon material was developed and defined by evaluating the effects of specific impurities and impurity levels on the performance of silicon solar cells. Also, data was generated forming the basis for cost-tradeoff analyses of silicon solar cell material. Growth, evaluation, solar cell fabrication and testing was completed for the baseline boron-doped Czochralski material. Measurements indicate Cn and Mn seriously degrade cell performance, while neither Ni nor Cu produce any serious reduction in cell efficiency

    Utilizing Urban Living Laboratories for Social Innovation

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    Cities have long been recognized as potential hubs of knowledge, social and cultural diversity, jobs, education, public services, and infrastructure. Alongside these opportunities, however, cities also face a changing climate, reduced availability of raw materials and natural resources, and dwindling physical space for the built environment. These challenges are accompanied by increasing disparities in income and resultant social inequalities; mounting threats to human health, well-being, and food security; growing refugee and migration influxes; and demographic changes. These concerns and associated governance challenges increase the urgency for new socially, ecologically, and culturally sensitive approaches to urban development. Such approaches need not only to reduce human vulnerability and environmental footprints, but also to build social cohesion and support ecological sustainability, cultural integration, and the establishment of a shared identity between citizens within a just system of distribution and access to urban resources and wealth

    Orthography influences the perception and production of speech.

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    One intriguing question in language research concerns the extent to which orthographic information impacts on spoken word processing. Previous research has faced a number of methodological difficulties and has not reached a definitive conclusion. Our research addresses these difficulties by capitalizing on recent developments in the area of word learning. Participants were trained to criterion on a set of associations between novel pictures and novel spoken words. Spelling-sound consistent or spelling-sound inconsistent spellings were introduced on the 2nd day, and the influence of these spellings on speech processing was assessed on the 3rd day. Results showed significant orthographic effects on speech perception and speech production in a situation in which spelling–sound consistency was manipulated with perfect experimental control. Results are discussed in terms of a highly interactive language system in which there is a rapid and automatic flow of activation in both directions between orthographic and phonological representations

    Silicon materials task of the low cost solar array project. Phase 3: Effect of impurities and processing on silicon solar cells

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    The 13th quarterly report of a study entitled an Investigation of the Effects of Impurities and Processing on Silicon Solar Cells is given. The objective of the program is to define the effects of impurities, various thermochemical processes and any impurity-process interactions on the performance of terrestrial silicon solar cells. The Phase 3 program effort falls in five areas: (1) cell processing studies; (2) completion of the data base and impurity-performance modeling for n-base cells; (3) extension of p-base studies to include contaminants likely to be introduced during silicon production, refining or crystal growth; (4) anisotropy effects; and (5) a preliminary study of the permanence of impurity effects in silicon solar cells. The quarterly activities for this report focus on tasks (1), (3) and (4)

    Effect of impurities and processing on silicon solar cells. Volume 1: Characterization methods for impurities in silicon and impurity effects data base

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    Two major topics are treated: methods to measure and evaluate impurity effects in silicon and comprehensive tabulations of data derived during the study. Discussions of deep level spectroscopy, detailed dark I-V measurements, recombination lifetime determination, scanned laser photo-response, conventional solar cell I-V techniques, and descriptions of silicon chemical analysis are presented and discussed. The tabulated data include lists of impurity segregation coefficients, ingot impurity analyses and estimated concentrations, typical deep level impurity spectra, photoconductive and open circuit decay lifetimes for individual metal-doped ingots, and a complete tabulation of the cell I-V characteristics of nearly 200 ingots
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