This paper is the fourth in a series of studies on architectural planning of “free schools”. In this part, action observation and interviews were conducted. 1) Children could stably engage activities by recognizing where staffs are. 2) Staffs choose locations according to four factors: children's activities, staff's activities, the situation at the time, and physical space. 3) Spaces without staff's control are essential for children for creating their own world. 4) Position of the staffroom is very important in relation with children's activities. 5) Staffs make a situation easy for children to approach and join them when staffs are not directly interacting with children.
