Recebido em 26/4/99; aceito em 31/5/99 THE HIGH SCHOOL CHEMISTRY CURRICULUM OF THE STATE OF MINAS GERAIS: PHILOSOFICAL FOUNDATIONS. This article presents the basic ideas that oriented the elaboration of the new Chemistry Curriculum for the High Schools in the State of Minas Gerais, Brazil. The main features of traditional Brazilian Chemistry Curriculum are critically discussed, namely, the excessive number of concepts, the overemphasis in procedures and rituals instead of chemical principles and the lack of relationship between the concepts and the social, technological and environmental contexts. Trying to overcome these features, the proposed curriculum deals with a fewer number of concepts, clearly related in a conceptual structure, opening space to a balanced emphasis on phenomena, theory and representation, and on conceptual and contextual aspects of chemical knowledge.

In this study, a teaching episode is analyzed to determine how a conflict is perceived as such and overcome by students as a result of the verbal interaction between the teacher and the students. The episode is part of a teaching sequence aimed at discussing the particulate nature of matter with students aged 15–16 years. In the task that generated the episode, the students observed a glass of water with a piece of rock and a ice cube and represented, by particles, the constitution of these three materials. The students represented the particles of ice closer than the particles of water, ignoring the observation that the ice cube floated on the water. The episode consisted of a discussion between the teacher and a group of students and shows the laborious construction of the conflict in the verbal interaction. The episode is analyzed by drawing from two different theoretical perspectives. The Piagetian theory of equilibration is used to describe the phases of compensatory construction in the students' attempts to deal with the problem. Analysis of the verbal interaction that resulted in the conflict's compensation is based on the work of investigators such as Vygotsky, Bakhtin, and Wertsch, and allows us to redefine the Piagetian constructs. The main theoretical issue raised by the present analysis is the shift from a personal perspective to a social one, which is a consequence of changing from personal construction to verbal interaction as the unity of analysis. © 2000 John Wiley & Sons, Inc. Sci Ed 84:429–444, 2000.

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RESUMO: A utilização de problemas sociocientíficos controversos nos currículos CTS demanda compreensão do posicionamento dos sujeitos, convidados na contemporaneidade a vivenciar uma nova relação com a ciência. Neste artigo analisamos um episódio de aula de Química no ensino médio. Com base na teoria da enunciação de Bakhtin, diferentes vozes foram trazidas para debate, momento em que focalizamos as interações discursivas sobre o efeito estufa e aquecimento global. Inicialmente os estudantes revelaram não ter consciência da natureza controversa do tema, além de criarem expectativas quanto a um posicionamento único e verdadeiro da ciência. Diferentes ritmos de apropriação da palavra do outro, acentos afetivos e ideológicos foram observados durante a tomada de consciência sobre a controvérsia. Palavras-chave: problemas sociocientíficos, interações discursivas, educação em ciências. DISPUTES OVER GLOBAL WARMING: MOVEMENT OF VOICES AND MEANINGS PRODUCED IN THE CLASSROOM ABSTRACT:The use of controversial socioscientific issues in the STS curriculum demands understanding of the positioning of subjects, invited in the contemporaneity to experience a new relationship with science. In this article we review an episode of a high school's Chemistry class. Grounded in the Bakhtin's theory of enunciation, different voices were brought into the debate, when we focus on the discursive interactions about the greenhouse effect and global warming. Initially the students sho-wed to be unaware of the controversial nature of the topic as well as creating expec-tations according to a unique and true scientific positioning. Different rates of others' word's ownership, emotional and ideological accents were observed during the increasing awareness about the controversy. INTRODUÇÃONo ensino de ciências, incluir problemas sociocientíficos no currículo significa, nas palavras de Sadler & Fowler (2006), situar problemas do mundo real como plataformas para que o aprendiz possa explorar conteúdos tradicionais por meio da realidade social, imersa na prática científica. Há um consenso entre entidades de vários países, AAAS 1 nos EUA, Royal Society na Inglaterra e MEC no Brasil, de que a habilidade de tomar decisões mediante problemas pessoais e sociais, com forte componente científico-tecnológico constitui um dos fundamentos para a formação de um cidadão contemporâneo. Os parâmetros curriculares nacionais citam a necessidade de se desenvolver a "competência de emissão de juízos de valor" (CNE,1998). Abordar situações controvertidas na sala de aula é uma demanda da sociedade atual por uma educação que prepare os sujeitos para um tempo de insurgência de incertezas. Educar em sintonia com essas mudanças de perspectiva significa, necessariamente, valorizar a dimensão controvertida da ciên-cia, a dúvida e o questionamento no interior dela.No presente trabalho analisamos os dois primeiros encontros de um projeto de ensino sobre aquecimento global e efeito estufa, desenvolvido durante aulas de Química em uma turma de 35 alunos da 1ª série do ensino ...

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