This study compared high school students' test scores using online instruction and traditional instruction. It is not known if, or to what extent, there is a statistically significant difference between students' academic performance in Algebra 1 when using online versus traditional instruction. This research study uses Zimmerman's self-regulated learning (SRL) theory as the foundation of study. This study is based on two research questions; R1: Is there a statistically significant difference between students' academic performance in Algebra 1 given online instruction compared to traditional instruction in the summer semester? R2: Is there a statistically significant difference between students' academic performance in Algebra 1 given online instruction compared to traditional instruction in the fall semester? The sample was archival test scores from remedial Algebra 1 in online (n=88) and traditional (n=90) instruction in a Texas school district. This was a quantitative ex post facto study and used an independent means t test for data analysis. There was no statistically significant (t (176) = -1.17, p = 0.244) difference between students' academic performance in Algebra 1 given online instruction (N = 88, M = 18.364, SD = 5.972) compared to traditional instruction (N = 90, M = 19.422, SD = 6.097) in the summer semester. There was no statistically significant (t (175) = -0.627, p = 0.532) difference between students' academic performance in Algebra 1 given online instruction (N = 88, M = 19.102, SD = 6.249) compared to traditional instruction (N = 89, M = 19.674, SD = 5.891) in the fall semester. This research study's findings concluded online instruction is comparatively equivalent to traditional instruction with remedial students in Algebra 1. [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.]