The teaching of metric units in Spain in the second half of the Nineteenth Century

In this article a historical research in mathematics education based on an analysis of ancient texts is described. The incorporation of metric-decimal units and its peculiarities in textbooks for primary used in Spain during the period 1849-1892 are highlighted. The sources were selected based on criteria defined through the purpose of the research. In their analysis, categories from the Didactic Analysis were considered. Through the study, different approaches that characterize the definition, presentation and usefulness of the metric-decimal units at this time were recognized. In the investigative process, the need to employ the scientific terms, and their development, an understanding of metrological equivalences, and the application of reductions in usual activities by memorization as a learning method are characterized.