“…Those who understood the hierarchical classification could explain pre-service teachers' reason related to the relation of quadrilateral properties, that some of them are subsets because of their special cases. However, in their understanding of the classification, although hierarchical, some were deficient in their concept images of parallelograms, as evidenced by the response in Figure 3, where this finding also occurred in preservice teachers (Birgin & Özkan, 2022). While those who have difficulties in understanding the hierarchical classification, use partial classification and refer to the quadrilaterals' different visual appearance.…”