Cálculo mental e a produção do conhecimento matemático

This text presents the research developed with students of the 5th year of elementary school at a public school in the city of Taubaté-SP, involved in solving problems involving the Mental Calculation. The read authors show that the Mental Calculation is relevant for the production of mathematical knowledge as it favors the autonomy of students, making it the most critical. Official documents that guide educational practices, such as the Parâmetros Curriculares Nacionais also emphasize that working with mental arithmetic should be encouraged as it has the potential to encourage the production of mathematical knowledge by the student. In this research work Completion of course the tasks proposed to students, who constituted the fieldwork to production data, were designed, developed and analyzed in a phenomenological approach. The intention, the research was to understand the perception of students in the face of situations that encourage them to implement appropriate technical and mental calculation procedures. We analyze how students express and realize the strategies for mental calculation in the search for solution to problem situations

Aplicação de carbono vítreo monolítico para produção de eletrodos a partir da resina furfurílica com diferentes variações de pH

Nowadays, we live in a time of rapid research for technological advances, in a way that this pursuit of new technologies is deeply connected to the diversity of new materials that have been developed by mankind. It deals with issues such as materials with enhanced properties which offer better quality, less cost and high performance, while they are accessible both in their production and moment of operation. In this context, it was required to develop electrodes that were easy to prepare as well as which present high electric conductivity and good mechanic proprieties by using carbonaceous material as basis. For this reason, the best parameters of the furfuryl resin cures were established with different pH variations through viscosimetric measurements and differential scanning calorimetry. By scanning electron microscopy (SEM) was possible to identify an increased porosity in the samples with pH 7 and pH 8, as compared to samples with lower pH content. After carbonization of the material, the characterization of monolithic glassy carbon was held by means of FT-IR techniques, Raman spectroscopy, X-ray diffraction and cyclic voltammetry. The spectra showed that the change in pH does not have significant influence on the crystallographic ordering of the material and its structural characteristics. As for the electrochemical character, the CVM electrodes showed excellent response, with good reversibility and wide potential window. Some voltammetric curve deviations were only observed for the sample with pH 4, which may be related to processing parameters adopted