Construção, aplicação e avaliação de um kit de experimentos para o ensino de eletrólitos
Rocha, Wilson Sergio de Araújo
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The limited information on electrolytes in high-school textbooks, the reduced time of weekly chemistry classes, and the lack of a laboratory in some schools suggest the need for an adaptation, for the teaching of this topic, with an experimental approach and using easily found materials. Thus, this work is focused on the development and application of a kit of experiments for use in the teaching of electrolytes, providing information on the construction (design and assembly) of an indicator of electrical conductivity and suggestions on how to apply the kit and evaluate the experimentally obtained results. This was done having Ausubel s meaningful learning theory as frame of reference. The developed kit comprises possible experiments for use of the indicator of conductivity as a tool for understanding the concept of electrolytes and questionnaires to collect the results obtained by the students. The kit was elaborated so as to make available simple classroom experiments, using easily found and daily used substances, and also seeking the scientific curiosity and motivation of the students, with safe handling and respect for the environment. The experimental activity, which may be addressed with an investigative approach, complements the theoretical exposition and should provide the students with a better understanding about electrolytes, thus contributing to the incorporation of knowledge and its relevant relationships. The kit was applied with four classes of students from a professionalizing public high school, encompassing: a diagnostic evaluation; a research-questionnaire (to be answered at home), followed by an evaluation; exercises in a worksheet (nº 1), carried out without and with the use of the kit of experiments; finally, exercises in another worksheet (nº 2). From the analysis of the results obtained throughout the application process, it was possible to conclude that there were evidences of student learning about electrolytes, rendered by the use of the kit of experiments. Hence, high-school teachers might use this kit as an auxiliary tool in the teaching of electrolytes and related topics and, in an interdisciplinary way, in the teaching of science, through experimentation.