What is a tool? A tool is “an implement or device used directly upon a piece of material to shape it into desired form” (Encyclopedia Britanica, 1987, Vol. 28, p. 712). This definition needs, however, four clarifications. First, the implement or device need not be a real object; it can be a symbol system serving as a tool for expression and communication (Goodman, 1978), a mental strategy by means of which knowledge can be transformed, and it can be a computer program allowing the manipulation and creation of symbolic materials. Second, a tool is not just an implement; it entails the purposes for which it is culturally or naturally designed to serve, the ways in which it is used, the techniques that are necessary for its usage, and the skill and knowledge that its usage requires (Ellul, 1964). It would be difficult to conceptually distinguish between a microscope, the device, and the scientific functions it is designed to accomplish, the ways in which it is properly used, the skills its use assumes, and so on. Clearly, using the microscope as a paper weight, rather than as what is was designed for, would still render it a tool but it would be an entirely different kind of tool, to be judged for effectiveness and efficiency relative to bricks and old plaster sculpturines of dancers rather than relative to other instruments of magnification.