The purpose of this quantitative ex post facto study was to examine the effectiveness of online learning amidst a global pandemic versus traditional learning and its impact on the achievement of secondary students. More specifically, the study investigated if there was a significant difference in the English Language Arts II test scores, Algebra II test scores, and Biology test scores between students who were enrolled in online coursework and students who were enrolled in traditional coursework. I used secondary deidentified data from the school district. The data collected from the school district came from the students who attended one of Tennessee's largest school districts. The students on whom the district collected data ranged in age from 14 to 17 and consisted of secondary students from the district's virtual school, which included approximately 917 students. The district-managed high schools, grades 9-12, consisted of approximately 23,500 students. I used the nonexperimental ex post facto design components to address the research questions within the study and the deidentified data collected from the school district were from the 2021-2022 academic year. Based on the findings of the study, the ELA I students' test scores did not have a significant impact on the ELA II students' test scores. The students enrolled in ELA II online coursework had mean scores higher than the students enrolled in traditional coursework. Also, the Biology test scores proved there was not a significant difference between the students' test scores enrolled in online coursework and the students enrolled in traditional coursework; however, students enrolled in Algebra II traditional coursework had higher mean scores than the students enrolled in online coursework. School administrators can use the findings from the study to implement best practices to help improve student achievement when it comes to online learning or traditional learning. School districts should make sure students are not isolated when it comes to online learning and find ways to implement and improve more hybrid courses, and school districts should continue to find creative ways to enhance the traditional way of educating students. [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.]