Utilização de indicadores naturais de Ph: uma proposta para o ensino de química.

Abstract

This study presented a proposal to Chemistry teaching, in order to stimulate the students´ interest. Moreover, it also shows the importance of practical activities using low cost instruments, in the teaching-learning process. The present work had the objective of evaluate the educational performance of students using the low cost experiment with red cabbage as a pH natural indicator in Chemistry class. The work took place in Fundamental and Intermediate Teaching State School Professor Deusarina Nascimento, situated in Benevides, Pará. The research was applied in four stages, in two different classes of the ninth year (experimental group containing 36 students, and control group with 20 students). The first stage consisted in a theoretical class titled “Inorganic Substances: acids and bases”. In the second stage a social and economic questionnaire, and a ten questions objective test about the theoretical class theme. In the third stage it was developed the experimentation with the pH measurements in the experimental group, while in the control group a traditional class was performed, which consisted in a list of exercises about the theme. In the last stage an evaluating test was applied again. The social and economic questionnaire application supported the idea that the students of both experimental and control group had the same social and economic status. The evaluating tests results leads to the conclusion that there was a weak output for both classes (experimental and control), but the experimental class helped in the memorization of the class content, much better than in the group control. Then, the work suggests an expansion of the research, concerning to other teaching-learning evaluating sistems, and proposes a new experimentation activity about the content.