In the present article the educational system is considered as a series of steps starting from the pre-school level and ending with the university level. The steps of education are in general consecutive, but there are some situations when some of them can be parallel. Each step is characterized by three parameters: level, filter and signal. The level characterizes all the contents of the given step, the filter is the test that must be passed in order to get to the next step, the signal is the certificate that confirms completion of a step, allowing a person to show society that he has passed the filter. Special attention is given to institutional discontinuities, i.e. cases when society refuses to trust the signals. (For example, universities do not rely upon the results of the matriculation exams and organize entrance exams of their own.) The paper indicates the threat of disintegration of the educational system and of the inclusion of extra-systemic institutions becoming built into it. (For example, the institution of private teachers.) It is suggested that a careful analysis of the educational system itself and of its efficiency requires combining the microeconomical approach (in the form of human capital theory) and the institutional approach (in the form of the theory of levels, filters and signals).