SUMMARY
In this article we take as a reference a research carried out in digitized files of the journal The School: Official Journal of Teaching, between 1900 and 1905, in search of information about arithmetic elementary knowledge for primary education present in copies of this journal. Our objective was to verify how these knowledge are reflected in the school exercises published in the journal. The theoretical-methodological contributions made to reach the objective are based on the concepts of expert, expertise, mathematical knowledge to teach and to teach, in its relations with the information about the mathematics present in the volumes of the journal that were researched. In this respect, we consider it essential to highlight the role of Francisco Ferreira de Vilhena Alves as an expert, whose insertions as editor of articles and sections of the journal, as well as from the comments on his work as an expert in education in the period in which the journal circulated, more specifically with regard to his work on the introduction of the decimal metric system in primary, secondary and especially the Normal School of Pará in the early twentieth century. The research showed that the arithmetic knowledge to be taught and to teach are materialized, interconnected, in the school exercises published in the journal, in an approach that Vilhena Alves considered adequate to guide the teacher in relation to arithmetic concepts and their teaching.