Poor science achievement has been an educational issue for a number of years. Students with disabilities have traditionally fared worse. Research suggests that students with disabilities may respond better to instruction using an inquiry-based approach vs. traditional textbook instruction when measuring science achievement on standardized measures. The researchers report achievement data on the Iowa Test of Basic Skills from a target school district for students' Individualized Education Programs (IEP) and non-IEP students, as well as students with IEPs at the state level. Using an argument-based inquiry approach to science instruction called the Science Writing Heuristic (SWH); the researchers report data supporting its impact on student achievement in science. Data suggest that the SWH may contribute to science achievement for students with IEPs.