of a specific discipline in France is the concept of "didactic transposition" (La transposition didactique in French). French philosopher and sociologist Michel Verret introduced this concept in 1975, which was borrowed and elaborated further in the 1980s by the French didactician of Mathematics Yves Chevallard. Although Chevallard initially presented this concept regarding the didactics of mathematics, it has since been generalized for other disciplines as well. Didactic transposition is composed of multiple steps. The first step, called the "external transposition" (transposition externe), is about how the "scholarly knowledge" (savoir savant) produced by the scholars, scientists or specialists of a certain discipline in a research context, i.e., at universities and other academic institutions is transformed into "knowledge to teach" (savoir à enseigner) by precisely selecting, rearranging and defining the knowledge which will be taught (the official curriculum for each discipline) and how it will be taught, so that it becomes an object of learning accessible to the learner. This external didactic transposition is a socio-political construction made possible by different actors working within various educational institutions: education specialists, political authorities, teachers and their associations define the issues of teaching and choose what should be taught under which form. Chevallard called this socio-political context of institutional organization the “noosphere”, which defines the limits, redefines and reorganizes the knowledge in socially, historically or culturally determined contexts. The second step, called the "internal transposition" (transposition interne) is about how the knowledge to teach is transformed into "taught knowledge" (savoir enseigné), which is the knowledge actually taught through the day-to-day concrete practices of a teacher in a teaching context, e.g. in a classroom, and which depends on their students and the constraints imposed on them (time, exams, conformity to prevailing school rules, etc.). In the third and final step, the taught knowledge is transformed into "learnt knowledge" (savoir appris), which is the knowledge as it is actually learnt by students in a learning context. The learned knowledge can be used as a feedback to the didactic system. Didactic research has to account for all the aforementioned steps of didactic transposition. Didactic triangle The teacher is given the knowledge or content to be taught to students in what is called a teaching situation. The teaching or didactic situation is represented by a triangle with three vertices: the knowledge or content to be taught, the teacher, and the student. This is called the "didactic triangle". In this