Scores on the Scholastic Aptitude Tests slumped in Virginia and Maryland last school year, while those enrolled in the District's private schools notched upward once again and those in the city's public schools slipped once again.

Nationally, the reading scores of the more than 1 million students who took the SAT college placement exams in the 1989-90 school year fell three points from the year before -- reflecting a long-term trend -- while their math scores held steady.

The continuing nationwide decline in reading prompted Donald M. Stewart, president of the College Board, which administers the SATs, to warn that students are spending too much time playing video games and watching music videos.

"Reading is in danger of becoming a 'lost art,' " Stewart said in a prepared statement that also highlighted a recent study by the National Assessment of Educational Progress. That study found that more than half of all high school seniors read 10 or fewer pages a day but spend at least three hours in front of a television set.

Maryland students, whose six-point gain during the 1988-89 school year was one of the largest increases in the nation, lost all of that improvement during the last school year, falling from an average combined math and reading score of 914 to 908. That is still above the national average, which now stands at 476 for math and 424 for reading, for a combined total of 900.

Bonnie Copeland, deputy state superintendent of education in Maryland, said she had no explanation for the six-point drop, though she said statisticians do not consider a shift of a few points to be significant. Last year, state education officials took credit for the six-point improvement, citing higher graduation requirements, increased state funding and other changes.

Copeland also said that 59 percent of Maryland's high school seniors took the test, which is voluntary.

The national average is 40 percent and, generally, the states with lower participation rates have higher scores because better students are more likely to take the test. The greater the participation, the more likely that average or poor students also are taking the test.

"That's not to say we're heartened by the results," Copeland said.

Virginia students, whose scores did not budge in 1988-89 from the year before, lost seven points in the most recent testing, leaving their combined total at 895 points, still higher than a decade ago. Virginia's participation rate was 58 percent.

Gerald M. Eads, the state testing supervisor, said the Virginia Department of Education would look for a reason for the drop, but Eads told the Associated Press that "Virginia has never specifically searched for causes of declining SAT scores."

The District's high school students registered their third consecutive increase, moving from a combined math and reading total of 846 to 850. But the increase stemmed entirely from the private school students, who represent an unusually large percentage of those taking the test in the District compared with Virginia and Maryland.

In the D.C. public schools, the combined score sank to 707 from 713, which itself was a decline of two points from the previous school year.

Pat Lambe, spokeswoman for D.C. public schools, said officials had not had time to analyze the data.

Continuing a long-established pattern both nationally and locally, there was a direct link between students' family income and performance: the higher the income, the higher the test scores. Likewise, the more years of education a student's parents had received, the higher the test scores.

Black students nationwide gained a point on their reading scores, climbing to 352, but dropped a point on their math scores, to 385. Since 1976, black students' reading scores have improved 20 points, however, and math scores have climbed 31 points.

White students lost four points on their reading scores -- 446 to 442 -- while their math scores held steady at 491. Since 1976, the reading skills of white students have fallen nine points and their math skills have dropped two points.

Jurisdiction.....1989.......1989......1990........1990.....% Tested

.................Verbal.....Math......Verbal......Math......(1990)

D.C..............407........439.......409.........441.........68

Maryland.........434........480.......430.........478.........59

Virginia.........430........472.......425.........470.........58

National.........427........476.......424.........476.........40

Note: Shown are average Scholastic Aptitude Test scores for 1989 in verbal and math categories; the 1990 scores; and the percentage of graduates who took the SAT in 1990. College Board officials discourage state-by-state comparisons because the percentage of SAT-takers varies widely among the states, and because the test-takers are self-selected. SOURCE: College Board