Fraction knowledge is known to be a gatekeeper to more advanced mathematical learning. On the basis of the literature on early number learning, a number line mobile application called Catch the Carrot was designed to develop students’ knowledge of whole number and fraction magnitude. This paper aims to describe the design of the Catch the Carrot app and discusses the rationale for using number lines as representational scaffolds for developing children’s understanding of numbers, particularly their estimat ion and number sense skills. The gamification features of the app, as well as strategies for integration in a classroom are also presented. This app, which utilizes number line representations, is expected to deliver the benefits associated with using numb er lines in instruction as suggested by the literature. The next step is to investigate the extent to which the gamified number line app promotes number sense and mathematical competence.

Twenty-four (24) Grade-11 senior high school students under the STEM track from a private university located in Quezon City took part in this study. Of the 24 participants who took the pre-test, only 23 proceeded with the eye-tracking test, where only 19 data were deemed treatable due to technical issues. This study examined different instantiations of mathematical blindness thru the lens of the Tripartite theory and with the help of the eye-tracking method that collected empirical data and aided in the investigation on how these instantiations manifested in participants’ mathematics problem-solving, particularly problems involving quadratic equations, ratio and proportion, geometry, and concept of speed. Other than the answers, solutions, and interviews recorded, quantifiable data were also extracted from the eye-tracker in addition to gaze movement and heat maps. Three instantiations of mathematical blindness were characterized in this study: (1) The Einstellung effect; (2) spurious correlation; and (3) intuitive rule. Among the three, the predominant instantiation of mathematical blindness observed was Spurious correlation.