Alexandria public school students scored about the same on national standarized tests administered last fall as they did the previous year, according to test scores released this week. Students scored well below the nationwide average in most categories, but generally were at or above their own tested ability levels.

School Supt. John C. Albohm, who is retiring in June, said he is pleased with the "holding power" of the test scores.

Albohm contended that the rapid absorption of minority students into the Alexandria school system is not reflieced negatively in the test scores.

There are more black than white sudents in Alexandria's public schools this year for the first time.

According to the test scores released this week, fourth-grade students averaged 44 on the ability-measuring tests (a score of 50 would place student exactly at the national average). Fourth graders scored above that level on tests that measured language arts, math, social studies, reading and science.

Sixth-grade student also averaged 44 in ability, and scored near that level in most categories. Eighth graders averaged 41 in ability, and slightly below in most tested areas.

At T. C. Williams High School, the only 11th and 12th grade public school in Alexandria, the ability average was 42. The average reading score was five points above, language arts averaged four points below, math was eight points above, science was six points below, and social studies was three points above. Alexandria school officials noted that differences become significant only if they vary more than five points from ability.

Dr. John Stubbings, director of secondary education, was asked why the science score was so low when T.C. Williams' science program and the students' achievements are so highly praised. He responded that the discrepancy "doesn't bother me in the least. We're more concerned with what actually happening (than test scores), and what's happening is good."

Stubbings added that the test measuring students' ability is "a paper and pencil test that lasts 20 minutes." He also noted that the tests are given to 11th graders the second month they are at T.C. Williams.

Supt. Albohm said there are many parents in Alexandria who are not able to afford tutorial help for their children - parents "who are not academically and status oriented" in contrast to other jurisdictions in the Washington area. But he said that Alexandria is able to provide its students with small class size, trained teachers, reading programs, and good facilities. Currently, there are about 13,300 students in the public school system.

Test scores varied greatly from school to school. At Patrick Henry Elementary School, which serves one of the city's most transient areas and has a student body which is 64 per cent black, fourth graders scored a low 29 in ability, but did well on individual tests when compared to their ability average.

Fourth graders at Charles barrett elementary school, which is located in the northern section of the city and has a student mix of 52 per cent white, 32 per cent black, and 16 per cent other, averaged a high 70 in ability, but scored below that in all other tested categories.

Alexandria students' average scores on achievement tests have been lower than scores in other Northern Virginia jurisdictions for a number of years.

According to the released scores, fourth graders did better last fall in reading, math, social studies and science than they did in 1975. Sixth graders did worse last fall in science than they did the previous year. Eighth graders scored lower in 1976 in reading, language arts, social studies and sciences. But in most grades and categories, the differences between the scores in the two years was slight, in some cases only a two-point change.