For you and for me, the category of the subject is a primary ‘obviousness’ (obviousnesses are always primary): it is clear that you and I are subject… - Louis Althusser

But someone is bound to question ... by what right I regard as Ideological State Apparatuses, institutions which for the most part do not possess public status, but are quite simply private institutions. As a conscious Marxist, Gramsci already forestalled this objection in one sentence. The distinction between the public and the private is a distinction internal to bourgeois law, and valid in the (subordinate) domains in which bourgeois law exercises its ‘authority’. The domain of the State escapes it because the latter is ‘above the law’: the State, which is the State of the ruling class, is neither public nor private; on the contrary, it is the precondition for any distinction between public and private. The same thing can be said from the starting-point of our State Ideological Apparatuses. It is unimportant whether the institutions in which they are realized are ‘public’ or ‘private’. What matters is how they function.

All ideology hails or interpellates concrete individuals as concrete subjects, by the functioning of the category of the subject. ... ideology ‘acts’ or ‘functions’ in such a way that it ‘recruits’ subjects among the individuals (it recruits them all), or ‘transforms’ the individuals into subjects (it transforms them all) by that very precise operation which I have called interpellation or hailing, and which can be imagined along the lines of the most commonplace everyday police (or other) hailing: ‘Hey, you there!’

What do children learn at school? They go varying distances in their studies, but at any rate they learn to read, to write and to add - i.e. a number of techniques, and a number of other things as well, including elements (which may be rudimentary or on the contrary thoroughgoing) of scientific' or 'literary culture', which are directly useful in the different jobs in production (one instruction for manual workers, another for technicians, a third for engineers, a final one for higher management, etc.). Thus they learn 'know-how'.