Transition from the preoperational stage of thinking to the concrete logical stage

In the theoretical part, I focused on the method and cognitive development theory of Jean Piaget, I presented the factors of cognitive development and described the course of development based on four specific stages of the development of thinking. I compared the mental operations (conservation, serration and egocentrism) and the differences between the answers that children provided, according to the level of thinking at which the child is. I also listed some critiques of Piaget's theory. The empirical part of the dissertation consists of a research that I conducted in kindergarten and the first and second grades of primary school. With these tests I tried to assess the stage according to Piaget's theory the children were at the time. I found out that most of the children were at a preoperational stage, which is reasonable for their age. The average age of the children who had reached the concrete operational stage was 7 years old, which is also appropriate according to Piaget's theory. However, some children had reached this stage already in the first grade of primary school, at the average age of 6 years and 3 months. I noticed some trivial differences between girls and boys, girls having had slightly better results in the tests