Les triangles semblables en classe de 2nde : Des enseignements aux apprentissages Etude de cas

摘要

This study focuses on the link between the organization of the teaching of similar triangles by a mathematics teacher in his or her class, and the learning it could provoke with pupils. We analyse pupils' results to a test in 5 classes of the first year of lycée (pupils 15-16 years old), by comparing every task of the test with all the tasks given in class before, and the conditions in which the pupils had to solve them, to try to understand why pupils succeed or fail for each task. It also allows us to analyse the teachers' practices in terms of regularity and differences.We analyzed the concept of similar triangles in the History of mathematics and in the school curricula since the beginning of the 20th century, to understand its place in today' teaching, and its link with geometrical transformations.