La razón y la fracción: un vínculo difícil en las matemáticas escolares

the role of the notion of ratio in the primary school mathematics, especially that of its link with the notion of fraction, are not clearly defined in the curriculum, at least in mexican's one, nor in classroom teaching. we share the point of view that attributes these difficulties mostly to the genesis of these notions, as well as to that of its teaching. in the first part of the text we present some relevant aspects of these geneses. in the second part, we stand out some of the various difficulties provoked by the link between ratio and fraction in the classes given by a teacher of sixth degree of primary school. we think that this analysis reaches to the comprehension of the problematic of proportionality teaching.