Teaching academic content to students with severe developmental disabilities is a topic that has recently been debated, even though science content is one of the academic areas that comprise a standards-based curriculum. Science content like other academic skills can be taught to this population using forms of systematic instruction, a validated evidence-based practice. In this study, three elementary aged students between 6 and 8 years old were taught units from an Early Science curriculum via inquiry-based lessons and effects were measured by a multiple probe design across behaviors (units). Visual analysis shows a functional relationship between the introduction of the intervention and a change in each participant's responding. These successful outcomes are discussed in light of other comparable work, the practicality of classroom teachers implementing similar lessons, social validity, and extending the knowledge-base of teaching science content to students with severe developmental disabilities.