SACRAMENTO, the United States, July 12 (Xinhua) -- Due to lengthy school closures, the academic performance of public school students in California, the most populous state in the United States, have returned to the levels of six years ago, a newly published report has found.

When California's academic testing resumed in 2022 after being suspended during the pandemic, researchers found "significant declines" in students' proficiency rates, according to the report by the Public Policy Institute of California (PPIC).

The think tank held a virtual presentation of the report on Tuesday, which aimed at examining the pandemic's impact on public schools and the state's educational recovery efforts.

In 2022, public school students' math and English Language Arts (ELA) scores were back at or below 2016 levels in nearly all grades, with the losses occurring across school districts, income levels, and races, according to the report.

The ELA scores fell by four percentage points and math scores dropped by 6.4 percentage points from the pre-pandemic levels, said the report, titled "District Spending of One-Time Funds for Educational Recovery."

While the declines were widespread, there is "substantial variation" across grade levels and demographic groups.

Low-income students, English Learners, and foster youth faced slightly larger drops in proficiency between 2019 and 2022.

Only 35 percent of low-income students met state standards in ELA, and 21 percent were proficient in math, compared to 65 percent of higher-income students in ELA and 51 percent in math.

Districts with the largest Latino populations saw the sharpest drops -- especially in math, where proficiency fell by 7.1 percentage points, the report found.

When schools were closed and teachers switched to online teaching, high-need students usually experienced longer school closures and were more likely to have limited access to the tools needed for virtual learning, according to the study.

However, the researchers also found, despite adverse schooling conditions, high-need students' test score declines were not as large as those for other students.

The U.S. National Assessment of Educational Progress (NAEP), a nationwide test of proficiency in reading and math, shows that California has consistently lagged behind most other states.

Among the 50 states and Washington, D.C., California is ranked 38th in math and 33rd in reading, according to a report released late last month.

Based on the NAEP results, researchers at the PPIC compared California's numbers to other similarly large states such as Florida, Texas, and New York.

Florida ranks much higher than California and the other two large states. California is ranked just above Texas in reading but far below in math, but the state ranks well ahead of New York in both math and reading, according to their analysis.

In fact, California's students had already lagged behind the national average before the pandemic started, and the disruptions further weakened the students' educational attainment.

Most of California's public school students spent the majority of the 2020 to 2021 academic year fully online, longer than students in other states.

Whether or not schools' reopening status impacted test scores was unclear, said the PPIC researchers, but they admitted that achievement losses were generally larger in districts that spent more time in remote instruction during the 2020 to 2021 academic year.

To jump-start educational recovery after the disruptions from the pandemic, the federal and state governments have sent billions of dollars in one-time stimulus funds to California's school districts.

These investments more directly targeted pre-existing lower achievement levels rather than pandemic-related learning loss, according to Tuesday's report.

Over 90 percent of school districts used the funding to accelerate learning -- small-group instruction, and 86 percent used the funds for student support, including meals, mental health, and social-emotional learning, the report said.

For assessing the recovery practices and improving funding programs, the PPIC researchers suggested streamlining funding sources and collecting better and more consistent data.