Accounting concept induces usually the idea of transactions expressible in terms of money in a system of interlocking statements in each of which total incomings are equal to total outgoings. It is known that, in a close system, the entries are not unrelated but are connected by a number of independent accounting identities. Thus, within an accounting framework we can build models in the certain knowledge that these connections will be respected, input-output analysis being the most obvious example of this kind of model-building. The application of elementary accounting ideas is not restricted to the concepts expressible in terms of money, but, for example, it can be applied to demography, with its obvious unit the individual human being, and to education, with its obvious unit the student. Such analysis can be applied in order to plan the educational system in a rational manner, based on demographic information that allows us to determine the flows of individuals with various characteristics into various activities, to show in detail the structure of the population at any time, and to design in the future how this structure may change under the impact of individual decisions or of those underwritten to economic and social aims.