QbyR: Proposal based on the use of a ruler to acquire rational numbers

<h2>Abstract</h2> By the end of primary education, students should know how to use natural, whole, decimal, and rational numbers. However, many difficulties arise in the teaching-learning process of rational numbers. This paper presents the <i>QbyR</i> device and method for acquiring rational numbers using graded rulers. The proposal is aimed at pupils in primary education who have not yet been instructed in the field of rational numbers, as well as pupils in higher grades who have difficulty with its acquisition. The results from the piloting of the exploratory study indicate that <i>QbyR</i> helps students acquire skills relating to the measurement of objects whose length is not whole and the use of mixed numbers at this educational level.