The purpose of this quantitative, quasi-experimental, nonequivalent comparison-group design was to determine if "How to Learn Math: For Students" (Boaler, 2018) had a statistically significant influence on ninth-grade and tenth-grade students' mathematical achievement and the achievement gap across socioeconomic status. Participants included ninth-grade and tenth-grade students (n = 19) in a suburban school district with a large population of economically disadvantaged students in eastern Pennsylvania. Students were given a pretest and posttest to measure both level of growth mindset and math achievement. Participants in the experimental group completed the online course "How to Learn Math: For Students" (Boaler, 2018) between the pretest and posttest. The results of the one-way ANOVA tests showed no statistical difference in math achievement, growth mindset, or the socioeconomic achievement gap. Therefore, the null hypotheses were accepted: the course had no effect on math achievement, growth mindset, or socioeconomic achievement gap. While the results were not significant, the findings of this study provide practical implications and recommendations for future research using this online course. [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.]