The purpose of this non-experimental causal-comparative study was to determine whether there is a statistically significant difference in the academic performance of high school students with and without disabilities who received math instructions in face-to-face and online educational settings during the 2020-2021 school year. During that year, educational establishments worldwide transitioned from traditional face-to-face to online delivery mode, complying with the social distancing requirements due to the COVID-19 pandemics. The current study employed a convenience sample that consisted of 588 high school students from Georgia. Participants took the Georgia Milestones End-of-Course Test in Algebra I in the spring of 2021 after receiving math instructions in the online or face-to-face settings. The researcher used this test as the instrument and compared the participants' scores. A two-way analysis of variance was used to examine the differences among six groups of students based on their disability status and the number of semesters taken online. The findings revealed that students with disabilities exhibited lower academic performance in math compared to their general education peers. Additionally, the study suggested that the transition to online learning during the COVID-19 pandemic had a negative impact on learning outcomes for all participants. However, the study did not find a significant interaction between students' disability status and the number of online semesters in relation to their academic performance. The limitations of the study included the specific population and quasi-experimental design. Recommendations for future research addressed the factors that may affect students' learning outcomes in online and face-to-face settings. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]