Interactive Multimedia (IMM) package has a greater potential of supporting individual differences of learners due to its inherent strength of media attributes. This study was carried out to explore the design features of IMM, which was specially designed to support the open and distant learners, studying Microbiology as a part of the B.Sc. Degree program, of the Open University of Sri Lanka (OUSL), with the purpose of explaining the dynamic abstract concepts in Microbiology. When designing the IMM emphasis was placed on the design features, interface design in particular, in order to help the learners to achieve a meaningful learning experience. The purpose of this research paper is to explore learner perceptions of the design features of the IMM and, in developing a more user friendly, authentic instructional package. As such, quantitative and qualitative research methods were used by means of questionnaires, interviews and observations. Evaluation reveals many supportive and constructive outcomes, and suggests improvements in providing a better support for learners studying science subjects at a distance. In the context of the university using new technologies, especially for delivery, the results of this study would be a great asset.