Since the 1970s, the National Assessment of Educational Progress (NAEP) has monitored student performance in mathematics and reading through long-term trend (LTT) assessments across three age levels (9-, 13-, and 17-year-old students). These assessments measure students' educational progress over long time periods to look for and monitor trends in performance. Although the LTT assessments are typically administered every four years, NCES decided to administer the LTT assessments for students ages 9 and 13 to provide data on post-pandemic student performance. The reading and mathematics assessments at age 9 were administered from January to March of the 2021–22 school year and the assessments at age 13 were administered from October to December of the 2022–23 school year. Approximately 7,400 age 9 students from 410 schools and approximately 8,700 age 13 students from 460 schools were assessed in each subject.