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O ensino de estatística no ensino médio através de projetos
(Universidade Federal de São Carlos, 2014-04-24) Dangió, Eric Giovanni Zenatti; Sampaio, João Carlos Vieira; https://lattes.cnpq.br/8286887389013685; https://lattes.cnpq.br/7841688982583063
The aim of this study was to reveal the results of a teaching experiment involving the efforts made in order to validate the teaching of Statistics in secondary school through projects and practices, which were contextualized and close to the reality of the students. The experiment is based on group work so as to provide students with significant cognitive advance. Didactic engineering was the methodology applied. During the experimentation, we developed a didactical sequence for teaching Statistics in secondary school, presenting the student with practical activities in which he could be the protagonist of the teaching-learning process. The results collected with the didactical proposal as well as the students participation in the activities were faced with the addressed hypotheses for the purpose of process validation. Although the National Curriculum Parameters - PCN for Primary School (Brazil, 1997 and 1998), PCNEM (Brazil, 2000) and PCN+ (Brazil, 2002) for Secondary School suggest that Statistics should be taught since the early grades, this subject is regarded as unimportant. In the state of São Paulo, the contents of Statistics are in the student's notebook, 4th volume of 3rd year of secondary school. However they are rarely addressed in class due to several factors, such as: students indiscipline, the resistance of some teachers to teaching that subject, the location of the content in the notebooks and insufficient time to properly work on the contents. Through the comparison of the results obtained with the analysis of the activities and the students participation, we conclude that the instructional sequence presented favored the development of the teaching and the learning of Statistics in secondary school.
Processos difusionais, cristalização e escoamento viscoso em dissilicato de bário vítreo
(Universidade Federal de São Carlos, 2014-04-24) Rodrigues, Alisson Mendes; Zanotto, Edgar Dutra; https://lattes.cnpq.br/1055167132036400; https://lattes.cnpq.br/1312261053452256
In this work, we analysed if the viscous flow successfully describes the transport of crystal nucleation and crystal growth structural units that occur at the liquid/crystal interface. In order to do this, we calculated the diffusion coefficient which controls the viscous flow, Dη, from experimental viscosity data using the Eyring equation and compared with diffusion coefficients that control the phenomena of crystal nucleation and growth (Dτ and DU), calculated from experimental measurements of specific heat, viscosity, crystal nucleation and growth. The analysis showed that the diffusion coefficient Dη satisfactorily describes the dependence of the diffusion coefficients Dτ and DU at high temperatures. However, for temperatures below 1.03Tg and 1.19Tg for crystal nucleation and growth, respectively, we observed a phenomenon called decoupling (or breakdown) that is the inability to use Dη. to describe Dτ and DU with temperature. This phenomenon was observed for other glassy materials and the values found in this study are consistent with the literature. All the experimental measurements performed in this study were obtained from the same batch of a stoichiometric glass with composition 33.3BaO.66.7SiO2-mol% where the chemical homogeneity was assessed (and deemed satisfactory) from a probability method using Poisson`s distribution. This work also proposed a new method to quantitatively measure the heating rate that should be used in a DSC furnace to prevent the formation of new nuclei. We then applied this method to the glass 33.3 BaO.66.7SiO2 and obtained the value of 25 °C/min. This value is in reasonable agreement with predictions from the literature that suggest a heating rate equal to 20 °C/min is sufficient to prevent the formation of new nuclei silicate glasses.