Augmented tabletops have recently attracted considerable attention in the literature. However, little has been known about the effects that these interfaces have on learning tasks. In this paper, we report on the results of an empirical study that explores the usage of tabletop systems in an expressive collaborative learning task. In particular, we focus on measuring the difference in learning outcomes at individual and group levels between students using two interfaces: traditional computer and augmented tabletop with tangible input. No significant effects of the interface on individual learning gain were found. However, groups using traditional computer learned significantly more from their partners than those using tabletop interface. Further analysis showed an interaction effect of the condition and the group heterogeneity on learning outcomes. We also present our qualitative findings in terms of how group interactions and strategy differ in the two conditions.