Open classrooms, embodying an educational policy and a setting departing from the traditional is said to provide especially good opportunities for environmental studies. An approach that summarizes a wide range of information on specific classes is a beginning to gathering environmental information useful to the deisgn process. This information includes what the room is like, the users and where they are located, and what they are doing and with whom. Each piece of information can be viewed in the context of a long-range and detailed backlog of data. Two urban elementary schools using open classrooms have been participating in a two year study of space use and behavior. Both operate a program using children's interests and a flexible use of space and learning materials. In order to provide the detailed information necessary for understanding how space is used, eight classes, four in each school, were selected for intensive study. Specific data gathering techniques included repeated observations of classrooms, repeated tracking, that is, following the complete days of individual children, interviews with teachers, children and parents, and the use of a model of the classroom in conjunction with an interview with students. A series of environmental workshops were also held with teachers and some children. This report concentrates on observations. (Author/JM)