A study observing children's participation in designing their own classroom space was based on the following framework: (1) creation of the environment and conditions necessary to enable children to express themselves constructively in a climate of acceptance; (2) support of children's need to prove and confirm their own abilities; (3) strengthening of the dynamics of the relations which develop among children of various ages when they cooperate in groups with a common goal and vision; and (4) establishment of the perspective needed by children so that they can obtain an integrated aesthetic perception and approach, through individual and group experiences, of a substantial intervention to shape, organize, and manage their own space. Children ages 3 through 5 attending 20 kindergarten and day care centers in Greece were observed as they played a "puzzle game" involving geometric shapes that represented their classroom. Findings included: (1) younger children tended to follow their own separate planning activities, while older children participated more in group planning; (2) space transformation and creation of multiple alternative solutions were usually first achieved by some of the children before becoming a kind of conquest by the whole group; (3) time spent completing a task varied from group to group and was dependent on the interest the activity presented for the children; (4) children in both free and participatory activities arranged or rearranged space according to their personal needs and aesthetic preferences; these preferences were expressed as pleasure in what they had achieved; and (5) a variety of forms of cooperation and mutual help were observed among children. (Includes a brief description of a planned follow-up study. Contains approximately 30 references.) (EV)