Étude de l’impact d'une remédiation impliquant le changement de prévalence conceptuelle sur les difficultés rencontrées dans l'apprentissage du concept de concentration en chimie : cas des élèves des séries scientifiques du Cameroun

Abstract

The concentration of a chemical species in a solution is a very fundamental quantity in chemistry and in several other fields of science. It is introduced into education in Cameroon in sixth grade (students aged 11 to 13). When handling it, learners encounter several difficulties in correctly determining the concentration of a chemical species in an aqueous solution. This research aims to evaluate the impact of remediation by change in conceptual prevalence on the scores of Cameroonian students in the scientific series (students over 15 years old) in general secondary education experiencing these difficulties. To achieve this goal, questionnaires were submitted at the pre-test phase to 528 students of Second C, First C and D and Terminal C and D classes of French-speaking Cameroonian education to bring out the said difficulties as well as the causes of the reasoning that leads to the erroneous answers that the pupils propose when they mobilize the concentration of a chemical species in aqueous solution. The results obtained at the end of this phase show that the most recurrent difficulties are: the inability of learners to correctly determine the concentrations of chemical species in a solution when the dissolution of a compound no longer takes place according to the proportion 1/1; the inability of learners to operate the formula for calculating the concentration of a solution (C = n/V) when determining the concentration of a chemical species in solution; incorrect mobilization of the intensive nature of the chemical concentration quantity when determining the concentration of a chemical species in solution. These same results show that the causes of these difficulties are mainly of the order of deficiency, ontological, epistemological and didactic. This study also compares the scores obtained in the post-test by two equivalent groups (60 students each) identified after the pre-test as having difficulty conceptualizing the concentration of a chemical species in solution. There are two remediation: one involves the change in conceptual prevalence and the other involves cognitive conflict. The results show that compared to a remediation involving mainly the cognitive conflict, the remediation by change of conceptual prevalence improves in a more significant way the scores of the learners. Thus, we can establish that a learning based on the change of conceptual prevalence allows Cameroonian learners to better overcome the difficulties they encounter when determining the concentration of a chemical species in a solution.