O que chamamos de produto natural? análise de sentidos e significados atribuídos a conceitos químicos ao longo de uma sequência didática contextualizada

Abstract

The abandonment of common sense knowledge, treated as an obstacle by scientists, does not represent the goal of civic education, as it is a knowledge developed through subject-subject and subject-world relationships, even though the product of these complex interactions may be a naive understanding of reality. Therefore, it is necessary for students to establish a critical relationship between the worldview they bring with them and the scientific knowledge acquired. In light of this, a didactic sequence (DS) was carried out with the instrumental aid of contextualization of knowledge present in the area of Natural Products Chemistry and folk medicine. The results indicate that students attributed different meanings to the term "natural product," with three general meanings distributed at different moments of the DS. The first meaning reveals that students have the idea that natural products are chemicals extracted from nature and beneficial to health. After discussing the social and historical importance of natural products, students come to establish that natural products are chemical substances produced by living organisms and not necessarily beneficial. However, students resist relating that the same substances can be produced in a laboratory. This meaning was modified after contextualizing chromatographic techniques and the preparation of extracts used in folk medicine, which required scientific concepts such as substance, mixture, purity, and chemical transformations. Students established that natural products are substances found in the form of mixtures and established that the different medicinal properties of the extracts result from the different compositions of the mixtures obtained.