Greg Toppo

USA TODAY

The good news on America's report cards: More high school teachers are handing out A's. But the bad news is that students aren't necessarily learning more.

Recent findings show that the proportion of high school seniors graduating with an A average — that includes an A-minus or A-plus — has grown sharply over the past generation, even as average SAT scores have fallen.

In 1998, it was 38.9%. By last year, it had grown to 47%.

That’s right: Nearly half of America’s Class of 2016 are A students. Meanwhile, their average SAT score fell from 1,026 to 1,002 on a 1,600-point scale — suggesting that those A's on report cards might be fool's gold.

The new findings come courtesy of two researchers: Michael Hurwitz of the College Board, the folks who bring you the SAT; and Jason Lee, a doctoral student at the University of Georgia’s Institute of Higher Education.

Hurwitz called the rise of the A average "really stunning."

The revelation comes as the USA's public high schools graduate a record number of students: The average high school graduation rate now tops 83%, according to federal statistics.

But that's not always translating into more college diplomas. A recent study by the Harvard Graduate School of Education found that just 56% of college students complete a four-year degree within six years of entering college. For students who start at two-year colleges, it's even worse: Just 29% earn a degree within three years.

Examining the academic transcripts of high school graduates in the 18-year period from 1998 to 2016, they found that the average grade point average (GPA) rose from 3.27 to 3.38, even as the average SAT score dropped.

Actually, they said, the upward creep is most pronounced in schools with large numbers of white, wealthy students. And its especially noticeable in private schools, where the rate of inflation was about three times higher than in public schools.

Hurwitz said an A is now "the modal high school grade,” a solid sign of grade inflation.

He said one of the goals of the research is to "make sure that college admissions professionals are equipped to make the best decisions possible.”

But he said high schools are increasingly moving away from class ranking, a traditional metric that helps colleges figure out which students are really achieving above their peers.

Lee said previous research has tied high school GPA to the National Assessment of Educational Progress, a widely respected standardized test administered by the federal government. But the new research is the first to draw such a direct line between GPA and SAT scores.

Recent research suggests that the problem isn’t just showing up in high school. In colleges nationwide, the most popular grade is now an A, according to Stuart Rojstaczer, a former Duke University scholar and founder of the website GradeInflation.com.

According to Rojstaczer, close to 50% of all college grades given are A’s, a far cry from even two decades ago, when the average GPA at a four-year college was 3.11.

He recently told USA TODAY that A’s are now three times more common than they were in 1960.

Rojstaczer has said grade inflation became more prevalent during the Vietnam War era, when professors began awarding higher grades to prevent students from being deployed, since students who dropped out of college were drafted into the military.

The new research is scheduled to appear in a book published in January by Johns Hopkins University Press.

Follow Greg Toppo on Twitter: @gtoppo