In this paper we describe a touchscreen application called "TouchCounts," which is designed to support the development of number sense in the early years. We first provide an a priori analysis of its affordances. Then, using Sfard's communicational approach, augmented by a focus both on the role of the body--particularly the fingers and hands--and emotions in the mathematical communication of a child, a teacher and a touchscreen device, we show how two 5-year-old girls learn about counting and adding.