This study sought to understand how students activate number sense in determining the position of fractions on a number line and identify how the natural number bias and number sense influences students’ thinking processes. The study utilized the Cognitive Task Analysis (CTA), involving four fifth-grade elementary students as the research subjects. The findings from this study suggest that students activate number sense in many ways, i.e. by comprehending the value and denominator of a fraction, dividing the number line into equal parts, and measuring distances based on fractions. However, the natural number bias could hinder students’ number sense, leading to their misunderstanding of the relationship between the fraction value and denominator. This misunderstanding may result in errors in comparing fractions, adding or subtracting fractions, and solving problems involving fractions. This study contributes to understanding the role of number lines in developing students’ number sense and formulating recommendations for mathematics teachers on how to identify and address the natural number
Rahayuningsih et al. (Mon,) studied this question.