MOPI elementary school is located in an urban but very green area of Rio de Janeiro, Brazil. It’s main façade faces a busy avenue that connects Rio´ s west and north zones. The opposite side of the building overlooks a national forest park with mountains, preceded by single family houses and lots of vegetation. The building was conceived as four separeted volumes connected by open balconies and derived from a “U” shaped whole open towards the forest. The two elliptycal volumes that faces the avenue contain the main classrooms, while the other two water drops shaped volumes contains secondary spaces such as administration, pedagogic room, art, library , computer classroom and so on. The whole building being split into four distinct volumes facilitates cross air circulation that provides passive cooling while marking very clearly the use purpose of each one. All levels are connected via 8% inclined ramps, to allow the inclusion of disabled students or professors. As ramps consumes a lot of space in plan to go from one level to the next, mid-levels were adopted. The top floor of the school, yet to be completed, will be a roof garden with grass and small trees overlooking the mountains with recreational and pedagogical purposes. Translucent channel glass encloses most of the classrooms, flooding it with light without distracting the students. The main façade evokes the forest, it is an abstraction of a tree. It is composed of micro perforated pre-oxidized copper panels attached to laminated wood beams, which are then attached to the concrete structure of the building. The wood used in these beams are a fast growing renewable material source, and it’s species (eucalyptus) are planted specifically to be harvested. Other environmental solutions adopted in Mopi want to achieve not only the sustainability of this building, but also the ecological sensibilization of the students such as: Storage and reuse of rain water, solar heaters for water, two phases toilet flushes, Taps with timers, and recycled materials like the rubber tiles on the ground floor. The micro perforation of the copper allows the passage of air while blocking rain water. It also gives the school a very lively aspect since it plays with transparency and opacity. During the day it looks opaque from the outside and semi transparent from inside. The green color dominates the façade. At night, it becomes semi transparent, letting movements and colors shine trough, making it come alive.