AbstractThe increasing use of microcomputers in classrooms opens up new possibilities for using visual, diagrammatic methods of teaching. This article sets out to explain why we sometimes abandon words and turn to graphical methods of communication. It is argued that a well designed graphical display can function as a kind of memory store. This view of the graphical display as a memory aid and a thinking aid suggests three principles for the program designer: parsimony, accessibility and reflection. ‘Progressive graphics’, where a display changes in step with the users' thinking, seem particularly suited to implementation on a compu