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 eighth-grade students' mathematical anxiety and mathematical achievement. Participants included eighth-grade students (n = 28) in a suburban public school in eastern Pennsylvania. Participants were divided into a control group and an experimental group depending on the class period in which they had mathematics class. Participants in both groups took a pretest and a posttest to measure mathematics anxiety and mathematics achievement. Participants in the experimental group completed the online course "How to Learn Math: for Students" (Boaler, 2018) between the pretest and the posttest in addition to their teacher lessons while participants in the control group participated in mathematics class as usual. The results of the paired-t tests showed a statistical difference in mathematics achievement from the pretest to the posttest, but no statistical difference in the mathematics anxiety scores. Therefore, one null hypothesis was accepted, and one null hypothesis was rejected. The findings show that the course had an effect on mathematics achievement, but not on mathematics anxiety scores. While the results were mixed, the findings of this study provide implications and recommendations for future research using the "How to Learn Math: for Students" (Boaler, 2018) 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.]