Mathematics in the initial pre-service education of primary school teachers in Portugal: Analysis of Gabriel Goncalves proposal for the concept of unit and its application in solving problems with decimals

This study aims to analyze Gabriel Goncalves didactic proposal for the initial approach of rational numbers in primary education, published in the 1974 edition of Didactic of Calculation (Didatica do Calculo). At a time where modern mathematical ideas began to influence mathematics education in the early years, it is important to understand how mathematics was addressed in the pre-service education of teachers of this school level. Among the themes approached in this textbook, the choice of rational numbers was due to the many difficulties that primary students usually have with this subject matter, as well as the teachers in teaching them. The study was conducted with a historical perspective based on documents analysis. The proposal of Gabriel Goncalves emphasizes the initiation of rational numbers through decimals instead of fractions and the different types of problems that should be presented to students in the initiation to decimals.