Classification logical function for preschool children and children of elementary-school age at the stage of representative intelligence

We have carried out the research of representative intellect genesis of 3 - 12 year-old children in terms of classification logical function formation. The experiment is done in the frames of the Geneva school genetic epistemology. We compared representative systems activity on the set site of intellect development. We set the problems, defined by intellect development multistage, divided by active phases of critical age. The critical phase of the intellect formation is revealed. It divides the preschool and school periods in seven years, as a transition period of active transformation of perception from figurative into logic. The technique of research can be used for qualitative diagnostics of childrens mental abilities.