The provision of information on mobile devices introduces interesting challenges. The most obvious of these is that ways have to be found of optimising the use of the limited available space; however, we also have to take account of the fact that, unlike many desktop-based tasks, activities carried out on mobile devices often require the user to attend to the external environment. In such cases, it is important that the device be able to provide relatively transparent assistance to the user's performance of a task in the real world.

Our focus is on the delivery of route descriptions via mobile devices: our contention is that, in this context, meaningful segmentation of information is a key element in meeting both of the above challenges. This paper describes our approach to developing a mode of interaction which supports the cognitive involvement of the user in performing the task of following a route description: we describe the technological underpinnings of the work and report on a pilot evaluation in a real task setting.