Research evidence concerning the effects of adaptive teaching and individualized learning remain relatively inconclusive, while there is obviously a need for better understanding how K-12 formal education may be more successful in addressing students' personal needs and interests, accounting for their diverse abilities with the main goal of advancing their learning. The proposed systematic review will not only rely on the most rigorous and comprehensive methodology of meta-analysis, but also should be conceptually sound (i.e., thoroughly exploring educational practices to find consistent links among a multitude of individual pedagogical approaches) and timely (i.e., account for the most recent developments in education). The main research question of the proposed meta-analysis is: Can more Student-Centred (SC) (i.e., more adaptive and individualized) approaches to K-12 instruction be distinguished from more Teacher-Centred (TC) approaches in terms of their effect on student achievements and what substantive and demographic factors moderate these effects? The review outcomes will inform education practitioners and research community of the best instructional practices, preconditions for their successful implementation and potential pitfalls, as well as of directions for further empirical research in the area.