We use Action-Process-Object-Schema (APOS) theory to study students' geometric understanding of partial derivatives of functions of two variables. This study contributes to research on the teaching and learning of differential multivariable calculus and its didactics. This is an important area due to its multiple applications in science,…

This research is a quasi-experimental study with the following objectives: 1) To examine the effectiveness of cooperative learning activities using the TAI technique combined with activity-based learning on the topic of congruence for students at Roi Et Rajabhat University, aiming to achieve the 75/75 efficiency criterion. 2) To compare…