Resumo Neste artigo, analisamos o engajamento mútuo de estudantes em aulas de Matemática que abordaram tópicos de geometria, fazendo uso de materiais manipuláveis. Para compreender o objeto de estudo, utilizamos a perspectiva da aprendizagem situada segundo Jean Lave e Etienne Wenger. Os dados foram coletados primariamente por meio da observação, mas também foram utilizados entrevista e documentos (registros dos estudantes) para ampliar os dados e subsidiar interpretações. Os resultados sugerem que o conhecimento da prática é mutável segundo as mudanças que ocorrem nas formas de engajamento. Estas formas são específicas e caracterizam outros engajamentos mais amplos. As seguintes situações de engajamentos foram caracterizadas: o engajamento de estudantes no contato preliminar com os elementos do material manipulável; o envolvimento de estudantes no recorte dos quadrados conforme as regras; o engajamento na associação do ângulo nulo à posição inicial dos palitos; o envolvimento na associação dos lados dos quadrados com os lados do triângulo.

Abstract In this paper, we analyze the mutual engagement of students in the development of mathematics lessons that addressed topics of geometry, in which manipulative materials were used. To understand the object of study, we used the Situated Learning Perspective according to Jean Lave and Etienne Wenger. Data were collected through observation, interviews and documents (student records during the tasks). The results suggest that the practical knowledge is changeable according to changes occurring in the forms of engagement, and featuring other broader engagement. Furthermore, we presented the following situational engagements: the engagement of students in primary contact with the elements of manipulative materials, the involvement of students cutting out squares according to the rules given, the association of engagement in a zero angle to the starting position of the sticks, and the involvement in the association with the sides of the square and the sides of the triangle.

No presente artigo, analisamos como professores operam a recontextualização dos textos dos materiais curriculares educativos na prática pedagógica e quais princípios regulam a operacionalização da recontextualização. A pesquisa realizada foi de natureza qualitativa e os dados foram coletados por meio da observação, entrevistas e documentos. A análise desses dados foi ancorada em constructos da teoria dos códigos de Basil Bernstein (1990, 2000) e sugere que a tarefa do material curricular educativo nem sempre é implementada de acordo com a intenção inicial dos seus elaboradores, ou seja, os professores operam a recontextualização dos textos dos materiais curriculares educativos para atender a princípios presentes na prática pedagógica. A identificação desses princípios indicam benefícios na produção de novos materiais curriculares educativos, materiais instrucionais e guias para professores.

In this article, we analyze how teachers operate recontextualization of educational curriculum materials texts in teaching practices and principles that govern the operation of recontextualization. The research was qualitative in nature and the data were collected through observation, interviews, and documents. The data analysis was anchored on constructs of the codes theory of Basil Bernstein (1990, 2000) and suggests that the task of the educational curriculum material is not always implemented in accordance with the original intention of its drafters, in other words, teachers operate recontextualization of texts of educational curriculum materials to meet the principles present in pedagogical practices. The identification of these principles indicates benefits in the production of new educational curriculum materials, instructional materials, and teacher guides.

A prevalência da infecção por Helicobacter pylori foi avaliada em uma população rural de Minas Gerais, Brasil, empregando uma reação de ELISA. Cento e quatorze de 131 adultos (87,0%) e 54 de 87 crianças (62,0%) apresentaram anticorpos anti-H. pylori. Foi observado aumento da prevalência da infecção com a idade (p < 0,001).

The prevalence of Helicobacter pylori infection was evaluated by ELISA in a rural population in Minas Gerais, Brazil. A total of 114 among 131 adults (87.0%) and 54 among 87 children (62.0%) presented anti-H. pylori antibodies and the prevalence of the infection increased with age (p < 0.001).

The prevalence of Helicobacter pylori infection was evaluated by ELISA in 40 children and teenagers and in 164 adults from a rural area of the State of Mato Grosso, Brazil. Antibodies to H. pylori were detected in the serum of 31 (77.5%) children and teenagers and in 139 (84.7%) adults. The prevalence of infection increased with age (c2 for trend, p < 0.01) even though no variations occurred in the region in the present century in terms of living conditions or sanitation, economical development and migratory influx supporting the hypothesis that the infection is also acquired during later life in developing countries. An inverse correlation was observed between the prevalence of infection and annual family income (c2 for trend, p < 0.013). There was no correlation between type of system for sewage disposal and prevalence of infection (p = 0.8). In conclusion, the prevalence of H. pylori infection in Nossa Senhora do Livramento, a rural area from Brazil, is very high and similar to that observed in other developing countries. Furthermore, the increase in the prevalence of infection with age observed in this population seems to be due to both, cohort effect and acquisition of the infection during later life