THE CATEGORICAL APPARATUS OF THE RESEARCH: THE SCIENTIFIC-PEDAGOGICAL ESSENCE AND INTERRELATION OF THE CONCEPTS “DIFFERENTIATION,” “DIFFERENTIATED APPROACH,” AND “DIFFERENTIATED INSTRUCTION”

Abstract

The precision of a scientific study depends directly on the clarity of its categorical apparatus. In contemporary pedagogical literature the terms “differentiation,” “differentiated approach,” and “differentiated instruction” are frequently used as synonyms, which generates terminological inconsistency and weakens the methodological foundation of research, particularly in the field of inclusive education. The purpose of this article is to clarify the scientific-pedagogical essence of these three concepts and to establish the logical and functional relationship among them. The study employs theoretical methods: etymological-terminological analysis, comparative-conceptual analysis, content analysis of foreign and post-Soviet pedagogical sources, systematization, and logical-structural modelling. The results demonstrate that the three concepts are not synonymous but form a vertically nested, three-level system: differentiation functions as a general scientific and pedagogical category (the genus concept), the differentiated approach operates as a methodological principle and strategic orientation, and differentiated instruction represents the procedural-technological level of practical realization. The article proposes a “category – principle – process” model that resolves the conceptual overlap and provides a coherent terminological basis for further empirical research on adapting teaching to learner diversity in inclusive settings