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A França, des de fa vint anys, els programes de química de batxillerat han introduït un model macroscòpic per a predir l’evolució dels sistemes químics. Aquest model macroscòpic, la reacció química, es distingeix de la descripció química de les modificacions del sistema, la transformació química. Aquest article presenta una anàlisi epistemològica i didàctica d’aquest programa així com una visió de la seva comprensió per part dels estudiants i els docents.paraules clau: Transformació química; reacció química, equació química, model., In the French chemistry syllabus of higher secondary school, 20 years ago, a macroscopic model was introduced to foresee the evolution of chemical systems. This macroscopic model, the chemical reaction, is distinct from the chemical description of the system modifications, the chemical change. This paper presents an epistemological and didactic analysis of this syllabus and an overview of how students and teachers understand it.keywords: Chemical change, chemical reaction, chemical equation, model.

The aim of this research was to investigate whether pupils aged 13, at the end of their first year of studying chemistry, are capable of perceiving the macroscopic and the submicroscopic level of the previously learned contents on chemical reactions, and whether they relate them to the chemical equations (the symbolic representation). Another aim was to establish how much demonstration experiments contribute to a better linking of the mentioned levels. The research featured 69 pupils of the seventh grade from three primary schools. The pre-test was conducted, following which experiments were demonstrated, and the post-testing was carried out in the end. After the intervention, a total of 12 pupils were interviewed about which aspects of chemical reactions they thought of based on the chemical equations. A statistically significant difference in two out of five requirements of the post-test, compared to the pre-test, indicate that the demonstration experiments may contribute to a better linking of three levels of representing chemical reactions. However, when one compares the pupils' answers in the test and in the interview, it can be observed that the correct answers in the test are not always based on understanding the concepts in connection with the chemical reaction.

The aim of this research was to investigate whether pupils aged 13, at the end of their first year of studying chemistry, are capable of perceiving the macroscopic and the submicroscopic level of the previously learned contents on chemical reactions, and whether they relate them to the chemical equations (the symbolic representation). Another aim was to establish how much demonstration experiments contribute to a better linking of the mentioned levels. The research featured 69 pupils of the seventh grade from three primary schools. The pre-test was conducted, following which experiments were demonstrated, and the post-testing was carried out in the end. After the intervention, a total of 12 pupils were interviewed about which aspects of chemical reactions they thought of based on the chemical equations. A statistically significant difference in two out of five requirements of the post-test, compared to the pre-test, indicate that the demonstration experiments may contribute to a better linking of three levels of representing chemical reactions. However, when one compares the pupils' answers in the test and in the interview, it can be observed that the correct answers in the test are not always based on understanding the concepts in connection with the chemical reaction.

The aim of this research was to investigate whether pupils aged 13, at the end of their first year of studying chemistry, are capable of perceiving the macroscopic and the submicroscopic level of the previously learned contents on chemical reactions, and whether they relate them to the chemical equations (the symbolic representation). Another aim was to establish how much demonstration experiments contribute to a better linking of the mentioned levels. The research featured 69 pupils of the seventh grade from three primary schools. The pre-test was conducted, following which experiments were demonstrated, and the post-testing was carried out in the end. After the intervention, a total of 12 pupils were interviewed about which aspects of chemical reactions they thought of based on the chemical equations. A statistically significant difference in two out of five requirements of the post-test, compared to the pre-test, indicate that the demonstration experiments may contribute to a better linking of three levels of representing chemical reactions. However, when one compares the pupils' answers in the test and in the interview, it can be observed that the correct answers in the test are not always based on understanding the concepts in connection with the chemical reaction.