Mississippi's learning gains nearly uniform across percentiles 

Percentile scores for 4th-grade reading

Based on data from the U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2005, 2007, 2009, 2011, 2013, 2015, 2017, 2019, 2022, and 2024 Reading Assessments.
Chart: Kelsey Piper and Eli Richman/The ArgumentSource: NAEP