In this paper the group size and the occupied area in children's free activities extracted by photos taken in each 10 minutes at children's nurseries were studied. Shapes of areas occupied by play activities were mostly consistent with the shape of situated activity areas they took place in and sizes of situated areas mostly matched the activity's needs. Following points also emerged: 1) Most groups had up to 6 members; 2) Area size of 2 tatami-mat, or even smaller in some cases, should be sufficient; 3) Shape types and activity kinds had different tendencies in size changing behaviors of activities.