The goal of this thesis is to compare adult and children strategy use on a fraction number line estimation. Students in Grade 4 (64), Grade 6 (66) and university students (30) will complete whole number and fraction number line tasks as well as other measures of fraction skills and math achievement. Strategy reports were collected on the 0-1 fraction number line task for all groups, and adult strategy reports were also collected on the 0-5 fraction number line task. Results showed that adults who used more strategies were more accurate on the 0-1 fraction number line task. Moreover, when comparing performance across fractions on the 0-1 fraction number line, adults performed similarly across all fractions whereas children were less accurate on the fractions in the middle of the number line. Implications of these findings for understanding the age-related differences in strategy use on a fraction number line are discussed.