EN
The author emphasises the importance of knowledge acquired by the teacher about his or her pupils as a necessary condition for effective education. There have been plenty of empirical data showing that the teacher's mental representation of the pupil is usually poor and distorted. In order to understand the motives of behaviour and experiences of his or her pupils the teacher should be equipped with adequate psychological knowledge about mental mechanisms of human behaviour, regularities of personality and social development of children and adolescents as well as individual differences.