The historical context of student grouping in education reflects diverse intentions and criteria. Researchers, teachers, and pedagogues have explored when to initiate grouping, its objectives, methods, and whether students should be placed in homogeneous or heterogeneous groups based on their abilities. They also consider the duration of such groupings and the inherent advantages or disadvantages they may present. In today's knowledge society, the focus shifts to helping individuals acquire quality knowledge and effectively utilize available human resources. With rising educational standards and increasing student diversity, the need for teaching differentiation and individualization has gained prominence. Experts now emphasize recognizing individual differences among students and ensuring that all receive quality, sustainable knowledge through appropriate organizational and didactic approaches. The principles of differentiation and individualization are crucial, as schools must cater to varying learning abilities while also fostering social integration and acceptance of diverse values. This monograph presents theoretical foundations and empirical research, analyzing the effects of different differentiation and individualization methods in Slovenia’s ninth-grade mathematics education, specifically examining the efficacy of teaching in homogeneous versus heterogeneous groups through cognitive and conative aspects, including exa
