Tangent lines are often first introduced to students in geometry during the study of circles. The topic may be repeatedly reintroduced to students in different contexts throughout their schooling, and often each reintroduction is accompanied by a new, nonequivalent definition of tangent lines. In calculus, tangent lines are again reintroduced to…

The focus of this study in which the theoretical framework of APOS was used is students' generalizing function notion from single variable to two-variable function concepts in Analysis II course in the elementary mathematics education program. In the teaching process, teaching activities that support generalizing the function notion with multiple…