An analysis of how the similarity of official documents and school texts was treated in the second half of the 20th century

Abstract

This work focuses on the development of similarity and Thales Theorem in the curriculum documents and mathematics textbooks belonging to 11-16 year olds level, during the last fifty years. The differentiation of the three moments in the historic development of similarity allows to identify three approaches to the concept when it is considered a teaching object. These different approaches and the way of establishing the relation between similarity and Thales Theorem are the aspects that I use in the analysis. The results show the great amount of restrictions that have influenced the teaching of the concepts and the different role that they play in the distinct periods considered.