The current study evaluated the effects of modified schema-based instruction (SBI) on the algebra problem solving skills of three middle school students with autism spectrum disorder and moderate intellectual disability (ASD/ID). Participants learned to solve two types of group word problems: missing-whole and missing-part. The themes of the word problems were related to their interests and daily experiences. In addition, participants were taught key mathematics vocabulary terms using constant time delay. Participants were taught how to use an iPad that displayed a task analysis with embedded verbal and specific verbal prompts to complete each step of solving the real-world algebra word problems. This study also examined participant’s ability to generalize skills when stimulus supports were faded. Results showed a functional relation between constant time delay and acquisition of mathematics vocabulary terms as well as between modified SBI and mathematical problem solving. Participants were able to successfully solve both types of group problems and had some success with generalizing skills when stimulus supports were faded. The findings of this study provide several implications for practice for using modified SBI to teach mathematical problem solving to students with ASD/ID, and offer suggestions for future research in this area.