The third in a series of leaflets designed for dissemination of information on school building, this publication describes the method of school building developed by the Centre de Rationalisation et d'Organisation des Constructions Scolaires (C.R.O.C.S.) in the Commune de Lausanne, Switzerland. In Lausanne, the concurrence of lengthening students' years in school with a rise in the school population created a need for 10 schools to be constructed between 1965 and 1975. Four architects agreed to collaborate to develop a rationalized system of building schools. Educators and architects actively participated in a study to define the spatial requirements, furniture, and equipment for, and the environmental needs of, modern teaching methods. The study resulted in an exhaustive brief of the architectural, technical, and financial requirements that would be basic to all new Lausanne schools. Graphic and narrative descriptions are provided of the geometry of the system; the primary structural elements; the secondary nonstructural and environmental elements; and the interior finishes, furnishings, and equipment. (Author/MLF)