Enseignement/apprentissage de la chimie : construction du concept de saponification en classe de terminale scientifique au lycee bilingue de nkoleton par l’experimentation

Abstract

The concept of "saponification" is one where the integrative element is the writing of its balanced equation, and its construction requires the mobilization of the concept of experimentation. However, it turns out that many learners in scientific classes, even after participating in a so-called "course" experiment according to Kane (2011), struggle to conceptualize the saponification equation. Thus, we aimed to demonstrate the impact of experimentation on the construction of the saponification equation among learners in scientific final-year classes. The main focus is to examine the relevance of experimentation as a mode of didactic transposition in teaching/learning the concept of saponification among students in scientific final-year classes through two activities: an analogical study between the formation and hydrolysis of a monoester and a triester, and the execution by the learners themselves of an experimental protocol primarily involving the various stages of soap synthesis in the laboratory. The study was conducted in Yaoundé, Cameroon, specifically with 118 learners from the scientific final-year classes at Bilingual Gouvernement High School of Nkoléton, where the sample was divided into two classes: one experimental class that received instruction based on experimentation and a control class that underwent traditional teaching. The experimental approach is structured into three phases: pre-test, test, and post-test. The final part of this experimental protocol includes 13 open-ended and semi-open-ended questions and tasks to which the learners were subjected. The "test" section focusing on analogy included 10 open-ended and semi-open-ended questions, allowing students to better conceptualize saponification. At the end of this process, after analyzing the results obtained, it appears that learners in the experimental group constructed the concept of saponification better compared to their peers in the control group who did not receive instruction based on experimentation. However, obstacles encountered by students in the experimental group suggest that better results could be achieved if concepts such as limiting reagents and stoichiometric proportions are integrated into the experimental approach while highlighting levels of knowledge.