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Susan B. Empson Debra Junk Higinio Dominguez Erin Turner 《Educational Studies in Mathematics》2006,63(1):1-28
Although equal sharing problems appear to support the development of fractions as multiplicative structures, very little work has examined how children's informal solutions reflect this possibility. The primary goal of this study was to analyze children's coordination of two quantities (number of people sharing and number of things being shared) in their solutions to equal sharing problems and to see to what extent this coordination was multiplicative. A secondary goal was to document children's solutions for equal sharing problems in which the quantities had a common factor (other than 1). Data consisted of problem-solving interviews with students in 1st, 3rd, 4th, and 5th grades (n=112). We found two major categories of strategies: (a) Parts Quantities strategies and (b) Ratio Quantities strategies. Parts quantities involved children's partitions of continuous units expressed in terms of the number of pieces that would be created. Ratio quantities involved children's creation of associated sets of discrete quantities. Within these strategies, children drew upon a range of relationships among fractions, ratio, multiplication, and division to mentally or physically manipulate quantities of sharers and things to produce exhaustive and equal partitions of the items. Additionally, we observed that problems that included number combinations with common factors elicited a wider range of whole-number knowledge and operations in children's strategies and therefore appeared to support richer interconnections than problems with relatively prime or more basic number combinations. 相似文献
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Jose M. Saavedra Antonio García-Hermoso Yolanda Escalante Ana M. Dominguez Raul Arellano Fernando Navarro 《Journal of sports sciences》2013,31(19):1783-1789
AbstractThe purpose of this study was to investigate the association between relay exchange block time and final performance in 4 × 100-m and 4 × 200-m freestyle and 4 × 100-m medley relays as a function of sex (men and women) and classification (medallists and non-medallists) in international competitions. Nineteen international competitions covering a 13-year period (2000–2012) were analysed retrospectively. The data corresponded to a total of 827 team relay histories (407 men, 420 women). Kruskal–Wallis and Mann–Whitney tests were performed to determine any differences by sex, classification, and event. Similarly, the relationship between the exchange block times and final performance was examined by means of a Pearson correlation analysis. In the three events, the men’s exchange block times were shorter than those of the women (η2 = 0.049–0.109; P < 0.001). The exchange block time was especially relevant for the women’s relay medallists in the 4 × 100-m freestyle (r = 0.306, P = 0.021) and 4 × 100-m medley (r = 0.385, P = 0.011), while for men the relationship was clearer for the non-medallists. These results suggest that the exchange block time should be considered as one of the performance parameters of swimming relay starts, and thus should be included explicitly as part of training. In particular, the coach could design training targeted at standardising an optimal exchange block time equal to or less than that expected for other teams in the competition. 相似文献
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Higinio Dominguez Carlos A. LópezLeiva Lena Licón Khisty 《Educational Studies in Mathematics》2014,85(1):143-160
In this paper, we explored how engagement developed over time during a proportional reasoning unit for a group of US bilingual Latino/a students, with particular attention to aspects of social and cultural activity that supported students’ engagement. Our findings suggest that student mathematical engagement developed primarily as a relational process characterized by students’ social relations across time, their understandings about their relationships with mathematics, and the important relations emerging across proportional reasoning ideas. 相似文献
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Xavier Ochoa Federico Dominguez 《British journal of educational technology : journal of the Council for Educational Technology》2020,51(5):1615-1630
Developing oral presentation skills requires both practice and expert feedback. Several systems have been developed during the last 20 years to provide ample practice opportunities and automated feedback for novice presenters. However, a comprehensive literature review discovered that none of those systems have been adequately evaluated in real learning settings. This work is the first randomised controlled evaluation of the impact that one of these systems has in developing oral presentation skills during a real semester-long learning activity with 180 students. The main findings are that (1) the development of different dimensions of the oral presentations are not affected equally by the automated feedback and (2) there is a small but statistically significant effect of the use of the tool when a subsequent presentation is evaluated by a human expert. 相似文献
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Using a Conceptual Understanding and Procedural Fluency Heuristic to Target Math Interventions with Students in Early Elementary 
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下载免费PDF全文 Matthew K. Burns Christopher Walick Gregory R. Simonson Lauren Dominguez Laura Harelstad Aleksis Kincaid Gena S. Nelson 《Learning disabilities research & practice》2015,30(2):52-60
The study examined the use of a conceptual and procedural framework for identifying math deficits and delivering appropriate interventions. Participants were two first‐grade students and one third‐grade student, who were identified as struggling with the grade‐appropriate content in math. The first‐grade students focused on addition and the third‐grade student focused on multiplication. Each student's conceptual understanding was assessed, and students who lacked conceptual understanding received an intervention that addressed underlying concepts. Students with acceptable understanding of the underlying concepts received an intervention that focused on the procedure. The study used a single‐case, multiple‐baseline design, but the contra‐indicated intervention was administered for the first 2 weeks following baseline, with the prescribed intervention for the final 2 weeks. Each student showed more growth during the prescribed intervention phase when compared to the contra‐indicated phase. 相似文献
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The aim of the study was to evaluate our practice of self-directed learning (SDL) among pre-university students in Malaysia. Respondents provided data on their previous school learning experiences besides present SDL experiences in college. We carried out exploratory factor analysis based on the school data. We did a confirmatory factor analysis using College SDL experiences of students. Given high similarities between the measurement models, we decided to use the original structure of the instrument. Students provided feedback using a questionnaire based on Prociuk’s. A large majority declared that they needed SDL experiences which they lacked while at school. The study also showed that students had rated their SDL experiences in college more positively than in school, on four factors of SDL experiences. Pearson correlations showed that “knowledgeable and organised teachers” and “promotion of active learning” correlated significantly with students’ current satisfaction with SDL in college. 相似文献
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Massimo GIUSTI Davide ORLANDI Giulia MELLE Barbara MASSA Enzo SILVESTRI Francesco MINUTO Gianni TURTULICI 《Journal of Zhejiang University. Science. B》2013,14(3):195-206
Ultrasonography(US) and the new applications US elastography(USE) and contrast-enhanced US(CEUS) are used in the screening of thyroid nodules,for which fine-needle aspiration biopsy(FNAB) is the best single diagnostic test.The aim of the study was to compare the sensitivity,specificity,positive predictive value(PPV),and accuracy of the four examinations in nodules with cytological and histological diagnoses.The study used data from US,FNAB,USE(elasticity(ELX 2/1) index),and CEUS(Peak index and time to peak(TTP) index) evaluated in 73 thyroid nodules in 63 consecutive patients likely to undergo surgery.Cytological-histological correlation was available for 38 nodules.No correlation emerged between nodule size and cytological results.A significant(P=0.03) positive correlation between cumulative US findings and cytological results was found.In addition,significant correlations between cumulative US findings and cytology(P=0.02) and between cumulative US findings and histology(P<0.0001) were found.US showed the best specificity and PPV,and FNAB the best sensitivity.There was no significant difference in the ELX 2/1 index,Peak index,or TTP index among nodules subdivided according to cytological scores.No significant correlation was found between ELX 2/1 index,Peak index,and TTP index,on the one hand,and nodule size,US cumulative findings,cytology,and histology on the other hand.The sensitivity of the ELX 2/1 index was high,but its specificity was very low.The accuracy and PPV of USE were lower than those of the other procedures.Only the correlation between Peak index and cumulative US findings reached a value close to significance.Our ultimate aim is to minimise unnecessary thyroidectomy.US and FNAB continue to play a central diagnostic role.The use of a US score showed high specificity and PPV.The specificity of FNAB was low in this selected series because of the numbers of indeterminate cytological responses.USE and CEUS are innovative techniques that need to be standardized.The ELX 2/1 index,Peak index,and TTP index seem to be unrelated to histology.The best statistical data on USE and CEUS concerned their sensitivity and PPV,respectively.At present,USE and CEUS are too time-consuming and of limited utility in selecting patients for surgery. 相似文献