Oficina de Corantes Naturais: Aprendizagem de Química Através de uma Sequência Didática Contendo Experimentação

Resumo

Natural dyes have been increasingly explored as sustainable alternatives to synthetic dyes in textile applications. Due to their structural diversity, varied sources, and extraction methods, natural dyes offer a rich and engaging context for teaching Chemistry in a creative and motivating way. This work aimed to design and implement a hands-on workshop for high school students, focusing on the extraction of natural dyes from common sources such as beetroot, black beans, hibiscus, annatto, onion peels, turmeric, and red cabbage. The workshop was developed to contextualize key chemistry concepts in an engaging and practical manner, addressing topics such as mixture separation, pH, organic functional groups, and intermolecular interactions. Implemented with first- and second-year students from two schools, the workshop was divided into three sessions: The first session consisted of a theoretical class covering the chemical principles behind the practical activities. In the second session, students performed the extraction of natural dyes and participated in a discussion circle. In the third session, they applied the extracted dyes in a cotton fabric dyeing activity using the tie-dye technique, integrating art and science. Student learning was assessed through a questionnaire containing both open-ended and multiple-choice questions related to the workshop content. The results showed that first-year students from the two schools achieved scores of 51 and 68%, while second-year students scored 66 and 87%, respectively, demonstrating the effectiveness of the activities. Some Chemistry topics considered more abstract remained challenging for students, as reflected in lower scores on related questions, even with the use of active learning methodologies. Nevertheless, the activities clearly fostered student engagement and autonomy. Students carried out all practical tasks independently, actively participated in the learning process, and had their voices heard, especially during the discussion circle. Undoubtedly, students were able to connect Chemistry to their everyday lives, seeing it beyond chemical formulas.