The aim of this study is to design various instructional materials to teach biological systems in a 'Systems in Our Body' unit to 6th grade students with visual impairment (SVI) and to evaluate the effectiveness of these materials. In the study, a design-based research model was used. In the first stage, individual learning needs of SVI and their understanding of biological structures in the 'Systems in Our Body' unit were determined. In the second stage, instructional materials matching the individual needs were designed and implemented. In the last stage, the usefulness of these materials and their effects on learning were explored. As a result of the study, it was seen that designed instructional materials made positive contributions to students' learning and understanding.