TYPES OF EDUCATIVE INTEREST
A higher form of activity involving the sensori-motor apparatus of the body is found when the control over external objects is achieved by means of tools of some sort, or by the application of one material to another. The use of a saw, a gimlet, a plane, of modeling-sticks, etc., illustrate the intervention of tools. The use of a thread in sewing, the application of heat and moisture in cooking or other simple experimentations, illustrate the use of one thing (or mode of energy) to bring about a change in another thing. There is, of course, no sharp distinction, either in practice or in principle, between this form of activity and the more direct kind just discussed. The organs of the body—especially the hands—may be regarded as a kind of tools whose use is to be learned by trying and thinking. Tools may be regarded as a sort of extension of the bodily organs. But the growing use of the latter opens a new line of development so important in its consequences that it is worth while to give it distinctive recognition. It is the discovery and use of extra-organic tools which has made possible, both in the history of the race and of the
