This paper examines some of the theoretical and practical problems associated with the use of hypertext as a medium for teaching, and explores the positive role that it may be able to play in teaching materials. Hypertext is conventionally described as non-linear, and this aspect of non-linearity is interpreted as endowing it with many attractive features. An alternative perception is that hypertext is a fragmented text form, and hence fundamentally flawed as an expository medium. The conventional rhetoric for hypertext is based on the limited concerns of information retrieval and attempts to subordinate linearity in the text. However, an alternative rhetoric is possible based on the aspect of hypertext which is most likely to aid learning, its malleability. An attempt is made to distinguish between the parts that can be most usefully played by linear and non-linear elements in educational texts and an idea is developed of a more general computer assisted instructional document encompassing linear prose, non-linear hypertext, and other multimedia devices. A learner controlled instructional rhetoric is possible for hypertext based on its malleability, and its use in a supplementary role within the context of a more general document form offers considerable potential for education. (15 references) (Author/DB)