61

This article analyzes a teaching-learning sequence in evolutionary biology intended for students aged 14 to 15. The analyzes are carried out in terms of structuring the contexts, according to an approach that is both epistemological and didactic. They document the logic of construction of the socio-epistemological context of the concept of natural selection and the dynamics of evolution of the problematic, intersubjective and intra-subjective contexts during the sequence. The heuristic dimensions of modelling by structuration of contexts allow us to produce a double sheet grid to develop the population thinking and the concept of natural selection. It leads us to identify highly functional language scenarios and language gestures in the construction of a relevant context with regard to the concept of natural selection. It shows the double movement of introducing scientific concepts into learning formal situations by the teacher, starting from the construction of the tasks offered to the students taken care of or accompanied by adjusted didactic language gestures.