Danielane said:I don't know, but it's not a school: it's the normal way to prepare the ENS exam.
Danielane, this might be a language misunderstanding: in English, a university is also a school (and a college too, for that matter) . Having been myself schooled in France, I'm pretty much aware of how the school system works there, and that one can't say in French "je vais à l'école" when one is doing a prépa/prep course, but one can say in English "I go to school" in that case...