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'.