Onto-genetically, human development means going through some mono-directional phases, from the biological to the cognitive development, followed by the emotional-affective development, to end with the socio-moral and the psychodynamic one. The biological development represents the sum of all morphological and physiological transformations that take place throughout one’s life. The cognitive development - as part of development as a whole - consists in a forming, shaping and completion process of knowledge structures, which also includes other sides of development (emotional, affective, social, moral, psycho-dynamic). The emotional-affective side is the part which consists of alterations of the capacity to have emotions and feelings during childhood and adolescence, subjectively felt as satisfaction or dissatisfaction, pleasure or the lack of it, close-ups-rejections, individually or as a group. The socio-moral development refers to taking-up some social and moral norms and rules by a person in order to regulate behavior. The psycho-dynamic development means body motion acquisition both in quantity and in quality along the ontogenetic process, more frequently in the first years of life. To sum up, the child needs to reach to a specific level of socialization where not only the psycho-dynamic development itself would suffice, but also a means of perceiving and considering the qualities of the people he/she is in direct contact with, in order to fit and cooperate effectively with people around. Piaget’s theory has been, is and will remain a general approach to the cognitive development, implicative both in education and in social development.