WASHINGTON — More high-schoolers are getting top grades but these students at the top of their class aren’t doing as well on the SAT college-entrance exam as A pupils in the past.

That has educators wondering if an A today still stands for academic achievement.

Since 1988, the percentage of high school students with A-plus, A and A-minus grade point averages has risen to 38 percent from 28 percent. At the same time, the SAT scores of that same group of students fell an average of 12 points on the verbal section of the test and 3 points on math.

“We don’t know why grades are rising,” says Donald Stewart, president of the nonprofit College Board that administers the SAT. “The way grading is taking place is somewhat suspect. I think there is a penchant to grade students less rigorously than in the past.”

Teachers sometimes are pressed by parents and administrators to give good grades, but the teachers union has no evidence that this is happening on a grand scale, said Robert Chase, president of the National Education Association.

“No one wants to see grade inflation,” Chase says. “It’s a red flag, but I’m not ready to say that’s what’s occurring.”

Top achievers aside, the average math score for high school students who took the SAT improved slightly this year. But the students didn’t do any better than last year on the verbal section, which tests reading, sentence completion and words, the College Board said.

Students taking the test had an average math score of 512, up a point from last year and the highest in 27 years. The average verbal score was 505 — exactly the same as last year and just 6 points above record-low verbal scores in 1991 and 1994.

The verbal score for Maine students was 504 and the math score was 501. Sixty-eight percent of Maine students take the test compared with a national average of 43 percent.

According to a survey of the 1.2 million college-bound students who took the test, grades have risen in all high school subject areas during the past 10 years.

Critics complain that students themselves supply their grade point average to the College Board on SAT registration forms. The board says it has sampled grade information and is confident students are not lying about their grades.

A recent UCLA study found similar evidence of grade inflation: More than 30 percent of 30,000 college freshmen studied in 1996 reported high school grade point averages of A-minus or above, compared with 22 percent a decade earlier.

Patricia Riordan, dean of admissions at George Mason University in Fairfax, Va., says she thinks grade inflation is not as rampant as some people believe. “We’re definitely seeing more students entering with Advanced Placement courses, but we don’t see any evidence that there is any change in grading. The grades look pretty fair,” she says.