Análise de uma sequência didática investigativa com o foco nos cálculos estequiométricos e no estudo dos sabões e detergentes
Data
2019-05-31
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Editor
Universidade Federal de Viçosa
Resumo
A Química é uma Ciência que estuda os materiais, suas propriedades e transformações, abordando conceitos relativamente abstratos. Para uma melhor compreensão dessa Ciência é necessário transitar por três níveis: (i) o macroscópico (descritivo), no qual é possível ver e manipular materiais distintos por meio dos sentidos; (ii) o representacional (simbólico), que utiliza fórmulas e equações químicas para atribuir sentido conceitual às transformações da matéria; e (iii) o submicroscópico (explicativo), relativo ao mundo dos átomos, moléculas, íons e espécies químicas em geral que nos são inacessíveis a olho nu. Assim, um dos conteúdos estudados no Ensino Médio que necessita contemplar estes três níveis seria o de cálculos químicos. Entretanto, a compreensão dos três níveis representacionais tem se mostrado desafiador para muitos professores e estudantes, comprometendo o ensino e a aprendizagem deste conteúdo. Diante disso, contextualizou-se o tema investigado neste trabalho com base no estudo dos sabões e detergentes, tendo esta pesquisa uma abordagem qualitativa que foi classificada, quanto ao procedimento, como participante. Com o objetivo de sondar as principais dificuldades para se compreender os cálculos químicos, bem como alguns dos fatores que poderiam contribuir para a melhor aprendizagem desse conteúdo, foi aplicado para 23 estudantes da 2a Série do EM, de uma escola particular no município de Viçosa (MG), um questionário escrito contendo dez questões de cálculos químicos e interpretação dos conceitos envolvidos. Os pressupostos teóricos e metodológicos relativos à Análise de Conteúdo proposta por Bardin foram utilizados na sistematização dos dados. Posteriormente, elaborou-se uma Sequência Didática Investigativa (SDI) sobre este conteúdo, que foi trabalhada em oito aulas com duração de cinquenta minutos cada. A sequência didática teve como foco o trabalho com a Alfabetização Científica (leitura do mundo por meio da Ciência), além de assumir um viés interdisciplinar abordando aspectos relacionados à Química Ambiental (Química dos Sabões e dos detergentes), em diálogo com os conteúdos abordados. Para analisar as aulas, foram elaborados estudos de caso, tendo como fonte as transcrições dos áudios das aulas, as respostas dos estudantes nos materiais escritos, além das impressões e anotações da professora ao longo do processo de ensino (notas de campo). Inicialmente, a análise do questionário de sondagem apontou dificuldades dos estudantes nos cálculos matemáticos, na interpretação do enunciado dos exercícios e na compreensão dos conceitos químicos (mol, massa molar, número de Avogadro, volume molar). Assim, foi verificada a necessidade de trabalhar os cálculos estequiométricos por meio de uma proposta de ensino contextualizada, o que fomentou a elaboração e aplicação da SDI contextualizada focando os cálculos estequiométricos. A análise dos dados demonstrou que ao abordar esse conteúdo em sala de aula com atividades experimentais investigativas que trouxeram questões sociocientíficas e fomentaram debates, o professor pôde problematizar o conteúdo, proporcionando aos estudantes um ensino mais dinâmico e participativo, o que possibilitou uma melhor compreensão dos cálculos químicos, assim como a promoção da Alfabetização Científica.
Chemistry is a part of Science that studies materials in general, their properties and transformations, approaching abstracts concepts. For a better understanding of this Science it is necessary to pass through three levels: (i) the macroscopic (descriptive), in which it is possible to see and manipulate different materials through the senses; (ii) representational (symbolic), which uses chemical formulas and equations to assign conceptual meaning to explain matter transformations; and (iii) the submicroscopic (explanatory), relative to the atoms, molecules, ions and chemical species in general that are inaccessible to us with the direct view or using a microscopic. Thus, one of the contents studied in High School that needs to contemplate these three levels would be the Stoichiometric. However, the understanding of the three representational levels has been challenging for many teachers and students, compromising the teaching and learning of this content. Thus, the topic investigated in this study was contextualized based on the study of soaps and detergents. Considering methodological aspects, this research was a qualitative approach that was classified, as regards the procedure, as a participant. With the objective of probing the main difficulties to understand the Stoichiometric, as well as some of the factors that could contribute to the better learning of this content, was applied to 23 students (15-17 years old), of a private High School at Viçosa town (Brazil), a written questionnaire containing ten questions of Stoichiometric and interpretation of the concepts involved. The theoretical and methodological assumptions related to the Content Analysis proposed by Bardin were used in the data systematization. Subsequently, an Investigative Didactic Sequence of Learning Science (DSLS) was elaborated on this content, which was applied in eight classes lasting fifty minutes each. The DSLS focused on the Scientific Literacy (reading the environment through Science explanations), in addition to taking an interdisciplinary bias addressing aspects related to environmental discussions (Chemistry of Soaps and detergents). In order to analyze the activities, case studies were elaborated based on transcripts of the classroons audios, the students' responses to the written activities and the teacher's notes and notes throughout the teaching process (field notes). Initially, the analysis of the questionnaire pointed to students' difficulties in mathematical calculations, in interpretation of the exercise statements and in understanding of chemical concepts (mol, molar mass, Avogadro number, molar volume). Thus, it was verified the need to discuss the Stoichiometric calculations through a contextualized teaching approach, which fomented the elaboration and application of the contextualized DSLS focusing on the Stoichiometric studies. The analysis of the data showed that when addressing this content in the classroom with experimental and investigative activities that brought socioscientific questions and fomented debates/argumentation, the teacher was able to problematize the content, giving the students a more dynamic and participative teaching strategy, which made possible a better understanding of the Stoichiometric, as well as the promotion of Scientific Literacy.
Chemistry is a part of Science that studies materials in general, their properties and transformations, approaching abstracts concepts. For a better understanding of this Science it is necessary to pass through three levels: (i) the macroscopic (descriptive), in which it is possible to see and manipulate different materials through the senses; (ii) representational (symbolic), which uses chemical formulas and equations to assign conceptual meaning to explain matter transformations; and (iii) the submicroscopic (explanatory), relative to the atoms, molecules, ions and chemical species in general that are inaccessible to us with the direct view or using a microscopic. Thus, one of the contents studied in High School that needs to contemplate these three levels would be the Stoichiometric. However, the understanding of the three representational levels has been challenging for many teachers and students, compromising the teaching and learning of this content. Thus, the topic investigated in this study was contextualized based on the study of soaps and detergents. Considering methodological aspects, this research was a qualitative approach that was classified, as regards the procedure, as a participant. With the objective of probing the main difficulties to understand the Stoichiometric, as well as some of the factors that could contribute to the better learning of this content, was applied to 23 students (15-17 years old), of a private High School at Viçosa town (Brazil), a written questionnaire containing ten questions of Stoichiometric and interpretation of the concepts involved. The theoretical and methodological assumptions related to the Content Analysis proposed by Bardin were used in the data systematization. Subsequently, an Investigative Didactic Sequence of Learning Science (DSLS) was elaborated on this content, which was applied in eight classes lasting fifty minutes each. The DSLS focused on the Scientific Literacy (reading the environment through Science explanations), in addition to taking an interdisciplinary bias addressing aspects related to environmental discussions (Chemistry of Soaps and detergents). In order to analyze the activities, case studies were elaborated based on transcripts of the classroons audios, the students' responses to the written activities and the teacher's notes and notes throughout the teaching process (field notes). Initially, the analysis of the questionnaire pointed to students' difficulties in mathematical calculations, in interpretation of the exercise statements and in understanding of chemical concepts (mol, molar mass, Avogadro number, molar volume). Thus, it was verified the need to discuss the Stoichiometric calculations through a contextualized teaching approach, which fomented the elaboration and application of the contextualized DSLS focusing on the Stoichiometric studies. The analysis of the data showed that when addressing this content in the classroom with experimental and investigative activities that brought socioscientific questions and fomented debates/argumentation, the teacher was able to problematize the content, giving the students a more dynamic and participative teaching strategy, which made possible a better understanding of the Stoichiometric, as well as the promotion of Scientific Literacy.
Descrição
Palavras-chave
Estequiometria, Química - Estudo e ensino
Citação
SILVA, Aline Aparecida Teixeira da. Análise de uma sequência didática investigativa com o foco nos cálculos estequiométricos e no estudo dos sabões e detergentes. 2019. 91 f. Dissertação (Mestrado em Química) - Universidade Federal de Viçosa, Viçosa. 2019.