Date of Conferral



Doctor of Education (Ed.D.)




Tammy Hoffman


Math achievement for U.S. high school students identified with math disabilities continues to fall below expected norms. Longitudinal national and state-level assessment data showed a flat or negative trend in math performance of students with disabilities, which may negatively affect their postsecondary outcomes. The purpose of this embedded mixed-methods study was to determine the impact of an extended time algebra course on increasing the math performance of freshman students with math disabilities. The conceptual framework included Vygotsky's sociocultural theory and zone of proximal development, Bloom's theory of master learning, and Carroll's theory of degree of learning. Data collection included archived test scores from the previous school year of 21 students and a survey administered to 4 current teachers of the Tier 2 course. Statistical analysis of the archived scores using an independent samples t-test measured the differences between the means test scores of students from the Extended Time course and the Special Education Algebra course. Additionally, the study used a paired samples t-test to measure pretest and posttest differences in math scores of students enrolled in the intervention course. Results from the t-tests along with coding of the qualitative data indicated that the Tier 2 intervention did not allow students to make statistically significant gains in math performance. Suggestions for improving the Tier 2 course were created based on study findings. The study is significant to high school educators inclusive of classroom teachers, school and district administrators, and curriculum developers because it examined an intervention used for students with disabilities who received educational support in the mainstream classroom. Results can inform best practices for meeting the needs of high school freshman and assist in the development of programming options that positively affect the academic achievement of students with disabilities. Implications for social change include improving math outcomes of students with disabilities as a means of increasing their success in postsecondary endeavors.