“…As in the studies of Aravena and Gutiérrez (2016), Gualdrón (2011), Gualdrón et al (2020, Gutiérrez et al (2021), andSantos (2014), this research managed to identify the importance of developing teaching units based on van Hiele's (1986) model, since in the different tasks that were proposed in the development of the sections, reasoning in van Hiele's (1986) levels 1 and 2 were emerging, this implies the acquisition of the concepts of proportionality, similarity, and homothecy. The students went from not having a clear notion of similarity to constructing a definition for similarity, proportionality, and homothecy; from not identifying criteria for similarity to identifying and understanding the mathematical properties that remain invariant in similar figures; from not using visualization skills such as mental rotation (MR), and not communicating their arguments using an appropriate mathematical language to using visualization skills and processes to identify, for example, alternate internal angles or configurations in homothetic position, in addition to expressing their reasoning in a symbolic manner.…”