A number of researchers point that thinking may perform the function of organization of forthcoming actions. However experimental studies of the function rather often assume that children may act without any resort to the externally stated terms of the problem. In the experiment described thinking's planning function has been studied in the context of preliminary analysis of the terms. Basic lines of solving the experimental problems corresponding to individual peculiarities in establishing spatial-temporal relations between the elements of conditions have been revealed. Use of auxiliary means which help the children to comprehend their own operations and ways of reorganization of the problem is shown to be of special importance. The tendency to look for such means is an indicator of the theoretical mode of performing under the conditions created in the experiment.