Why do we need evaluation at school? The main purpose of the paper is to highlight the value of knowledge gathered by means of evaluation from the perspective of social studies. The article will look at forms of formative evaluation – evaluation through clarification, interactive evaluation and evaluation through monitoring. The paper will concentrate upon the practical value of knowledge gathered during evaluation research in schools, with the author attempting to find answers as to what evaluation means; the practical value of knowledge acquired by evaluation research; how a major discrepancy between the field of deep reflection on the essence and purposes of evaluation, and the field of practical action might be explained, and the reasons and consequences of the prevalence of bureaucratic evaluation. The article claims that the gap between reflection and pedagogical action, existing mainly in Poland, might be the main reason for the failure of evaluation research, arising from differences in how it is commonly understood and the definition given in the relative literature; evaluation frequently being identified with assessment.