Many multimedia chemistry courses fail to reach their full educational potential as they do not engage the learner in a meaningful task or give appropriate feedback. Though molecular modelling is a recognised technique widely used in chemistry to enable students to grasp difficult concepts, tutorials often do not afford students either the time or scope to learn by experimenting with molecular structures. In this paper we describe the educational development of a web based organic chemistry tutorial which aims to enable students to learn chemical concepts through the manipulation of structural formulae and the provision of appropriate feedback. An online chemical structure modelling tool was developed to enable molecules to be drawn online and to provide feedback. The aim of this study is to address key issues relevant to the development of educational resources of this nature. It will be of particular interest to teachers and lecturers working within Science and Engineering, audio–visual staff and educational developers.