Textualization and Educational Reforms: Analysis of a Praxeology in the Last Eighty Years

188 math textbooks for the secondary school printed during the last 80 years are analyzed. This analysis is based on the praxeologies related to the parabolas identifying the transformation of this piece of knowledge in the different books over time. The Anthropological Theory of Didactics (ATD) is adopted as well as the notions of didactic transposition, praxeology and the scale of didactic codeterminacy levels. This analysis shows a transformation in books that go from information systems to activity folders. Thus, we notice an impoverishment of knowledge over time.