This quantitative, nonexperimental study used Bronfenbrenner's process-person-context-time (PPCT) model to determine if mathematics scores of underprivileged, minority third- and fourth-grade students attending an inner-city school in a Central Oklahoma school district differed between their traditional 2018-2019 school year and post-lockdown 2020-2021 school year. In March 2020, the nationwide response to the COVID-19 global pandemic was to close all schools, disrupting the educational process for students, which may have caused significant learning loss, particularly in elementary mathematics. Analysis of the test results revealed a statistically significant difference in state test mathematics scores for both grades between the years studied. According to the t-test results, on average, the 2018-2019 (n = 73) and 2020-2021 (n = 84) third-grade students' math performance was significantly lower than their math performance before the pandemic forced students into a home-based, online learning environment, t(138.822) = 2.557, p = 0.006, d = 0.415. For 2018-2019 (n = 70) and 2020-2021 (n = 79), fourth-grade students' math performance after returning to school was significantly lower than their pre-pandemic math performance, t(147) = 2.536, p = 0.006, d =0.416. To compare differences between the two independent subject groups, the conclusion of the additional nonparametric Mann-Whitney U test (p = 0.0035) was consistent with the results from the t test. Future researchers can use the demonstrated significant loss of mathematical aptitude testing results as the starting point for future qualitative research. [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.]