In this paper I present the Sonic Blocks. A Tangible User Interface (TUI) for collaborative exploration of digital music with children. Based on the notion of exploratory Tangible User Interfaces this paper gives an account of the design, development and initial observations of the Sonic Blocks in use. The findings gathered from these observations reveal that TUIs through their physical engagement can enable unique approaches to thinking and cognition that contrast significantly to the visual model of interaction offered by the Graphical user Interface (GUI).