Children should be able to do their own experimenting and their own research. Teachers, of course, can guide them by providing appropriate materials,… - Jean Piaget

Knowing reality means constructing systems of transformations that correspond, more or less adequately, to reality. They are more or less isomorphic to transformations of reality. The transformational structures of which knowledge consists are not copies of the transformations in reality; they are simply possible isomorphic models among which experience can enable us to choose. Knowledge, then, is a system of transformations that become progressively adequate.

One must have felt a real desire to exchange thoughts with others in order to discover all that a lie can involve. And this interchange of thoughts is from the first not possible between adults and children, because the initial inequality is too great and the child tries to imitate the adult and at the same time to protect himself against him rather than really to exchange thoughts with him. The situation we have described is thus almost the necessary outcome of unilateral respect. The spirit of the command having failed to be assimilated, the letter alone remains. Hence the phenomenon we have been observing. The child thinks of a lie as "what isn't true," independently of the subject's intentions. He even goes so far as to compare lies to those linguistic taboos, "naughty words." As for the judgment of responsibility, the further a lie is removed from reality, the more serious is the offense. Objective responsibility is thus the inevitable result of unilateral respect in its earliest stage.

But these structures, forming different levels, are to be regarded as succeeding one another according to a law of development, such that each one brings about a more inclusive and stable equilibrium for the processes that emerge from the preceding level.