Test scores released on Thursday showed that American 9-year-olds' reading and mathematics achievement levels had dropped to levels last seen two decades ago, revealing the damage the COVID-19 pandemic has wrought on education in the United States.

The National Center for Education Assistance (NCEA) compared assessments conducted in 2020, shortly before COVID-19 was declared a worldwide pandemic, to others administered in early 2022 to measure how pandemic-related learning disruptions had affected the children's achievement.

The plummeting scores represent "some of the largest declines" since the NCEA began regularly monitoring student reading and math performance in the 1970s, according to the center's acting associate commissioner, Daniel McGrath.

In mathematics, Black students' scores declined by 13 points, compared with 8 points for Hispanic students and 5 for white students, part of a wider trend of minorities suffering disproportionately from pandemic fallout. Reading scores declined evenly by six points across racial groups from 2020 to 2022.

Lower-performing students across all races also experienced much greater declines than students in the top percentiles of both test categories.

For the NCEA's reading assessment, students read short texts and answer multiple-choice questions or write longer answers. For mathematics, students answered mostly multiple-choice questions about basic math facts, computations, formulas and real-life applications.

The study also surveyed students on how the pandemic had affected their learning environment, with 70% of students saying they recalled learning remotely at some point during the 2020-2021 school year.

Of the remote learners, 83% of students performing at or above the 75th percentile in reading and math had constant access to a computer or tablet, compared with 61% of students performing at or below the 25th percentile.

The NCEA said it plans to release a more comprehensive report later this year, including mathematics and reading results for students in 4th and 8th grades around the country, in each state and in 26 urban school districts.