Education is considered one of the main drivers of welfare in society. However, countries in the world follow different paths when creating basic human capabilities, many of them not in the right direction. Linear extrapolation is still widely utilized to predict future behavior based on statistics like the Primary Completion Rate. This paper presents a dynamic model of primary education as a first step to understand the structure and behavior of educational systems and as an alternative way to extrapolate outcomes of this and other relevant key indicators, like the Gross Enrollment Rate. The model is calibrated for the case of Nicaragua.