The goal of this research was to examine fifth graders' understanding of fractions on the number line. This case-study design focused on the various ways that students represented fractions on number lines. Students responded to task-based interview questions by identifying fractions as a number on the number line as well as equivalency and problem solving. The tasks were administered individually to 26 fifth-grade students over a 15-minute time frame in their respective schools. The two groups of 10-year-old students answered most questions in written form with pencil and paper and were often asked to explain how they arrived at an answer. Student performance was highest when instructed to plot one-half on a number line of 0 to 1 as well as naming a fraction less than one-half. The students performed lowest when they attempted to plot one-half, one-fourth, and 1 on a number line with a predetermined unit 0 to one-third. Other low performing concepts consisted of plotting one-fourth on a number line from 0-3, identifying one-fourth on a non-routine number line, and plotting a unit fraction with an equivalent fraction as well as an improper fraction on a common number line.