This study addresses content changes to be taught in the first years of elementary school. In particular, it considers the teaching of mathematics with a focus on the emergence of Modern Mathematics in Brazil. In a specific way, it examines the concept of number. It considers as a theoretical and methodological foundation studies originally from cultural history. The analysis considers the pedagogical movement prior to what is known as the Modern Mathematics Movement: traditional education, intuitive teaching and progressive era in education. It then takes into account the emergence, dissemination and appropriation of a new mathematics for schools in the [mid-20th Century / 1940s]. The article is guided by the following question: what changes does the concept of number undergo in the mathematics for schools in the late 1950s? As a result the study reveals how the production, distribution and appropriation of new mathematics content for children of elementary school took place.
primary education; arithmetic; Modern Mathematics Movement; number