This study investigated the effects of physical environment on children's behavior, mainly in open plan elementary schools. The survey is based on observation of children's behavior in several open plan schools. The results shows that 1) There are various kinds of territory made by class (class monopolistic territory, class prior territory, public territory) in open space. It is influenced by spatial composition and layout. 2) Some physical settings such as partition, book shelf, screen, etc. become boundary to divide territory. . 3) Most of children occupy the prior territory with some friend (they are perhaps moderate grouping). But if this space is small, children sometimes spread over to public place or neighbor place. The children occupied isolated place usually make a small intimate group. Intimate group sometimes occupy the well defined corner.
