Browsing by Author "Silva, Marina"
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- O mapa conceptual: uma estratégia de sistematização e relação de conteúdos em história e geografia de Portugal numa turma de 6.º anoPublication . Silva, Marina; Rato, Valter; Ferreira, Nuno MartinsO presente artigo tem por base um estudo realizado em contexto de Prática Profissional Supervisionada numa turma de 6.º ano do 1.º Ciclo do Ensino Básico. Partindo das características da turma, decidiu- se escolher como estratégia de ensino de conteúdos históricos e geográficos o mapa de conceitos ou mapa conceptual como forma de sistematizar e relacionar os diversos conteúdos abordados durante a prática pedagógica. Este recurso foi aplicado ao longo da intervenção, no final de cada unidade temática. Os alunos da turma em questão apresentavam grandes dificuldades em relacionar e sistematizar os conteúdos de História e Geografia de Portugal e também os de outras disciplinas. Este facto verificou-se, uma vez que possuíam hábitos de estudo incipientes e por nunca lhes ter sido apresentada esta técnica da História e Geografia – o mapa conceptual – como forma de relação e síntese de conteúdos. Identificadas as fragilidades, propôs-se trabalhar a seguinte questão- problema: de que forma o mapa conceptual potencia a síntese e as relações de conteúdos já abordados, influenciando o aproveitamento escolar dos alunos? Após a implementação de dois mapas conceptuais, verificou-se que os discentes apreenderam, de uma forma mais satisfatória, os conteúdos lecionados. Conseguiram, portanto, identificar o essencial de uma determinada categoria e estabelecer relações mais significativas que se encontraram espelhadas no momento de avaliação.
- Primary school pupils’ misconceptions of the human respiratory system in primary school students: from identification to deconstructionPublication . Silva, Marina; Almeida, AntónioThis study involved 38 students from the 6th year of schooling attending a state school in Lisbon in which the Science syllabus is centered on the study of human body systems. Its purpose was to determine: (i) whether the students possessed any of the misconceptions related to the human respiratory system referenced in other studies (e.g. air enters and leaves our bodies with no function, air tubes connect the lungs to the heart, the air exhaled is rich in carbon dioxide and poor in oxygen); (ii) whether a learning design focused on the deconstruction of these misconceptions would be effective to the conceptual change of these pupils. To this end, the experimental group (class A) experienced a learning design expressly conceived for the deconstruction of the misconceptions related to the human respiratory system, while the control group (class B) experienced a traditional approach with interactive lectures and use of the school textbook. The data were collected through a questionnaire administered in two stages (pre and post-test) and a t-test was used to compare the means obtained by the two groups in the pre-test and to verify the gains of each class between the pre and the post-test. After analysis of the results of the pre-test, it was found that the students of the two groups had several misconceptions of the human respiratory system. The experimental group had more significant gains, although the students in both groups reduced their misconceptions. Both results support the idea that formal education, if provided with well-structured activities, can contribute to the conceptual restructuring of the students’ mind, albeit with a different rate of success. Finally, the present study also helps to confirm the universality of certain misconceptions.
- Risk assessment of combined exposure to multiple chemicals: the case of mycotoxins exposurePublication . Viegas, Susana; Viegas, Carla; Ramos, Carla; Silva, Marina; Sabino, Raquel; Veríssimo, Cristina; Rosado, LauraBackground: It is well established that people are exposed to a diverse and dynamic mixture of chemicals as a routine part of their existence, and there is clear evidence that toxicity can be modified by simultaneous or sequential exposure to multiple chemicals. Nevertheless, risk assessments have focused mainly on exposure to individual chemicals in a specific environment via a single route or pathway. It has repeatedly been demonstrated that Aflatoxin B1 and ochratoxin A belong to the most frequently occurring mycotoxins. However, only just recently, the risk resulting from their simultaneous occurrence could be assessed due to new information about their combined biological effects. Materials and Methods: A descriptive study was developed to monitor air fungal contamination in 10 hospital food units. Five air samples of 250 liters through the impaction method were collected in food storage facilities, kitchen, food plating, canteen and also, outside premises since this was the place regarded as reference. Results and Discussion: Besides other fungal species, in one of the food units, Aspergillus flavus and Aspergillus ochraceus were isolated. After that, weight-of-evidence classification based in the work developed by Mumtaz & Durkin (1992) was applied to qualitative assess the weight of evidence for the interaction between aflatoxin B1 and ochratoxin A and it was possible to conclude that this interaction is likely to have relevance to potential human health effects. Conclusions: Limits for mycotoxins human exposure only consider the effects of each toxin by itself and do not take into consideration their combined effects. It is, therefore, necessary to revise it to permit performing more accurate risk assessments.