Piaget’s interest is to find the answer to the question how mental development of child is affected by the environment in which the young person lives. The milieu constantly causes difficulties which child has to overcome by interaction with the world, which process is the foundation for learning (Lynne 2001:2).

Thinking thus Piaget proposes assimilation and accommodation as two means which reinforce the process of learning. The development in which child does not experience any alteration is defined as assimilation, on the other hand, when child needs to adapt to a new situation such a process is called accommodation. He also maintains the view that assimilation and accommodation are primarily adaptive processes of conduct which as child grows older become so automatic as to be inherent in thoughts (Lynne 2001:3).

Piaget states that steady development of child’s reasoning abilities means an increase of knowledge and psychological abilities to the eventual capacity of formal, logical thinking. Moreover, this partial process is filled with various important changes, which make child go through a sequence of phases. The young person is able to understand some kinds of reasoning at each phase, yet unable to familiarize with. Piaget assumes that the age of 11 is a border which means that abstract reasoning in accordance with the laws of logic may be unattainable after it. What Piaget fails to take into consideration is the society, which plays an important role in Vygotsky’s theory (Lynne 2001:3). Piaget also states that we can assume that child is a “sense – maker”, which means that he is capable of acquiring knowledge about the world which surrounds him through his experience (Lynne 2001:4).