Abstract
Identified relationships between figures, based on their properties, is an
important characteristic of Level 3 thinking in the van Hiele theory.
However, there has been no research directed at how such relationships,
leading to class inclusion, evolve. This study, involving indepth interviews
with 24 secondary students, addresses this issue by considering their attempts
at grouping seven different triangle types. The results reveal important
features about perceived relationships between figures, and the existence of a
developmental path.
Penelope Currie and John Pegg
Is An Equilateral Triangle Isosceles? Student Perspectives