Nick Anderson of the Washington Post wrote on September 3, 2015.

Scores on the SAT have sunk to the lowest level since the college admission test was overhauled in 2005, adding to worries about student performance in the nation’s high schools.

The average score for the Class of 2015 was 1490 out of a maximum 2400, the College Board reported Thursday. That was down 7 points from the previous class’s mark and was the lowest composite score of the past decade. There were declines of at least 2 points on all three sections of the test — critical reading, math and writing.

The steady decline in SAT scores and generally stagnant results from high schools on federal tests and other measures reflect a troubling shortcoming of education-reform efforts. The test results show that gains in reading and math in elementary grades haven’t led to broad improvement in high schools, experts say. That means several hundred thousand teenagers, especially those who grew up poor, are leaving school every year unready for college.

“Why is education reform hitting a wall in high school?” asked Michael J. Petrilli, president of the Thomas B. Fordham Institute, a think tank. “You see this in all kinds of evidence. Kids don’t make a whole lot of gains once they’re in high school. It certainly should raise an alarm.”

It is difficult to pinpoint a reason for the decline in SAT scores, but educators cite a host of enduring challenges in the quest to lift high school achievement. Among them are poverty, language barriers, low levels of parental education and social ills that plague many urban neighborhoods.

Cyndie Schmeiser — chief of assessment for the College Board, which owns the SAT — said she is concerned because the share of students prepared for college has stagnated for five years. Close to 42 percent of students who took the SAT reached a score of at least 1550, a benchmark for college and career readiness. The share was far lower for Hispanic students (23 percent) and African Americans (16 percent).

“Simply doing the same things we have been doing is not going to improve these numbers,” Schmeiser said in a statement. “This is a call to action to do something different to propel more students to readiness.”