Article: Integrating the classical system after a Montessori school?

Whether they come from a Montessori, Freinet, democratic school, or any other type of alternative school, the students will sooner or later have to return to the classic system. In fact, these "different" schools are mostly for kindergarten and primary school, but only very exceptionally for secondary school. Thus, many parents are concerned about this readjustment to a more traditional system. So, is it really difficult for these students to re-enter a traditional school?