In this study, we developed a tablet-based application, namely ubiquitous fraction (U-fraction) to assist elementary school students to learn fraction with authentic contextual support. Three topics of fraction included are fraction concept/comparison, simplification and addition/subtraction. An experiment was carried out to investigate the effects of students' learning behavior toward their fraction learning achievements using U-fraction, which allowed students to explore and verify fraction learning in authentic contexts. Totally, 80 fifth grade students were assigned and divided into three groups, one experimental group and two control groups. The first and second control group learned fraction using web-based application and traditional teaching method, while experimental group learned fraction using U-fraction. After the experiment, the results shown the experimental group performed better than those in both control groups. The reasons were that the graphical representation in authentic context facilitated students to learn fraction using U-fraction. Multimedia whiteboard like text and voice explanation provided by U-fraction also helped students to do more practices by themselves and fully explain their solutions. Furthermore, this study revealed that learning behavior variable i.e. note-Taking (text), total fraction skill and assignment score variable had a significant correlation with post-Test. We also found students' perception toward the system were acceptable.