The advent of powerful and relatively cheap personal desktop computers has led to an explosion in software designed to provide information, entertainment, and education. In the eyes of many educators, however, the software that is purported to be educational has failed to deliver its promised potential. The consensus about this apparent failure is the use of an inappropriate instructional design model of computer aided learning or hypermedia. Earlier models of instructional design developed from the precepts and assumptions that underlie the behavioural/objectivist pedagogy of teaching and learning. This thesis examines instructional design of hypermedia in chemistry from a pragmatic constructivist pedagogy of teaching and learning. This interpretive study explicated students' preinstructional knowledge of the topic 'rates of chemical reactions' by means of concept mapping and interviewing. The emergent hypotheses in the data reconstruction resulted in three major assertions that address students' prior knowledge constructions, students' non formal language and students' shared lifeworld constructions. Five implications for instructional design which evolved from the assertions argue that students' preinstructional knowledge constructions can be used to enhance meaningful learning of chemistry. The implications support: the incorporation of students' lifeworld knowledge constructions; the use of non formal language; valuing students' lifeworld experiences; developing propositional linkages between students' more common alternative frameworks and formal concepts; and developing propositional linkages between the macroscopic and molecular view of chemistry. The final component of the study proposes a new model of hypermedia design. The model supports meaningful learning in chemistry by providing: an individualised approach to learning by students; and a framework to develop propositional linkages between students' preinstructional knowledge constructions and formal chemical concepts.