The article reacts on the current needs based not only in the educational practice and pedagogical theory, but also in the requirements of the society. These requirements focus on the pupils' competences that have to be able to think rationally, to deal with the new situations, and to solve problem situations. Conceptually, this paper concentrates on the issues related to the terminology, which are arising mainly from the pedagogical theory that is nowadays limited by an unsatisfactory degree of completion in the field that is aimed on the inquiry-based instruction. With the application of the inquiry-based instruction (not only in Czech Republic) closely related to the development of the pedagogical theory, there emerged a problem of the terminological basis. The inquiry-based instruction is neither well-known nor understood what the term itself means. Therefore, this paper focuses on the resolution of a comparatively well-defined area of the pedagogical reality which, however, has a broader context when discussing other related scientific fields--psychology, philosophy, and technology. The outcome of this article is to specify the term inquiry-based instruction from the various points of view in a form of a definition that characterizes the basic elements contained in it.