This study designed a learning system to facilitate elementary school students' fraction learning. An experiment was carried out to investigate how the system, which runs on multi-touch tabletop versus tablet PC, affects fraction learning. Two groups, a control and experimental, were assigned. Control students have learned fraction by using tablet PCs while experimental students have learned fraction by using multi-touch tabletop. It was found that learning effect of multi-touch tabletop was greater than that of tablet PCs. Multi-touch tabletop enabled students to easily collaborate, to learn fractions as well as to practice their problem-solving skills. On the other hand, students tended to work individually when using tablet PCs; therefore, students' collaboration was limited and their understanding of fraction concept could not be promoted. As multi-touch tabletop was found as more beneficial to students' learning, this study has further investigated the relationship of research variables (i.e., learning behavior to use the system and interaction among peers) with learning achievement in multi-touch tabletop environment. According to results, the number of times that fraction cards were canceled positively correlated with the post-test results. The reason is that canceling cards enabled students to refer to symbolic, graphical and simplified representations of fractions; thus, students could analyze fraction-related problem more thoroughly and solve it more efficiently. This study revealed that "seeking help" and "giving help" are important variables in peer interaction, particularly, in tightly collaborative multi-touch tabletop learning environment and they could lead to better learning achievement. With obvious awareness of peers' needs and availabilities in multi-touch tabletop learning environment, students have easily asked for help from and provided help to peers during problem-solving process. In contrast, control students have usually worked individually or in loose collaboration. Results of this study also showed that most students had positive perception toward the multi-touch tabletop system, high collaborative learning attitude and motivation. Based on above-mentioned findings, this study makes several implications along with conclusions and suggestions for the future research.