Differentiated instruction offers opportunities to improve student academic performance, specifically in students with learning disabilities. However, teachers' perceptions of which differentiated-instruction program works best to support differently abled students were unknown. The purpose of this qualitative case study was to explore teachers' perceptions on whether face-to-face instruction using response to intervention or computer-based learning using TenMarks works best in improving the academic performance of students who are differently abled in mathematics, specifically geometry. Constructivism, social disability theory, and Bandura's social learning theory formed the study's theoretical framework. Research questions guiding the study focused on teachers' perceptions of the advantages and challenges of traditional face-to-face instruction versus TenMarks when educating differently abled students. Data were collected through one-on-one interviews and member checking using a purposeful sample with six high school mathematic teachers. Thematic data analysis followed an open coding process to identify emergent themes. The findings showed that teachers perceived advantages and challenges with both instructional models. Further, teachers believed combining the two approaches would be most beneficial as the strengths and weaknesses of the two approaches are complementary, which correlates with disability's social and critical models. This study contributes to positive social change through school administrators and teachers in guiding school policies and practices related to differentiated-instruction approaches in classrooms that include differently abled students.