Using National Assessment of Educational Progress (NAEP) data over a 50-year period, Hanushek et al. (2019) observed that the socioeconomic achievement gap in the United States has failed to close. Plotting standard deviations between the 90th-10th and 75th-25th percentiles of socioeconomic status revealed that the achievement gap remained relatively consistent over time. This consistency held when comparing students based on free or reduced-price lunch eligibility. However, the racial achievement gap between African American and White students decreased during this period. Additionally, while 8th-grade students (ages 13-15) made learning gains, 12th-grade students (over age 17) showed slower gains. The authors conclude that the persistent achievement gap reflects a relative Matthew Effect rather than an absolute one.