This paper presents a system for interacting with digital information, called Triangles. The Triangles system is a physictidigital construction kit, which allows users to use two hands to grasp and manipulate complex digital information. The kit consists of a set of identical flat, plastic triangles, each with a microprocessor inside and magnetic edge connectors. The connectors enable the Triangles to be physically connected to each other and provide tactile feedback of these connections. The

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... nnectors also pass electricity, allowing the Triangles to communicate digital information to each other and to a ,desktop computer. When the pieces contact one another, specific connection information is sent back to a computer that keeps track of the configuration of the system. Specific two and three-dimensional confi,%ations of the pieces can trigger application events. The Triangles system provides a physical embodiment of aigital information topography. The individual tiles have a simple geometric form which does not inherit the semantics of everyday physical objects. Their shape, size, and connectors encourage rapid rearrangement and exploration of groups of Triangles. The infinitely reconfigurable 2D and 3D topographies of the Triangles system create a new language for tangible interface. Keyworcis Interface design, tangible interface, physical interface, graspable interface, digital connector, physical connector, magnetic connector, tangible bits. lNTRODUCTlON Physical building blocks are powerful tools for thought and play. They allow quick construction and manipulation of structures through two-handed tactile interaction. This enables an easy exploration and understanding of the blocks' interactions with one another, and also of physical properties lie balance, gravity, composition, and form ( Fig. 1) .