The design for the extension of the Alliers de Chavannes nursery school draws on its context within the landscape and its integration within the site. The three new volumes that house the extension connect to the longitudinal circulation of the existing building in such a way as to allow them to be perceived as separate pavilions. The existing building is reconfigured to become the school's spine. Distinguished by two types of metal cladding - galvanized steel and anthracite zinc - the new volumes provide a visible distinction between the original building and its extension. The new volumes are organized to ensure fluidity and a programmatic organization in harmony with the existing functioning of the school, logically inserted between the trees and providing views of the surrounding vegetation. Elevated on steel stilts and with facade openings offering each space a variety of orientations, the extensions allow pupils to imagine that their school is a tree house!