Alexandria students in grades one through four on the average have steadily increased their performance during the past five years, while sixth and seventh graders' performance has shown some decline, according to the latest achievement tests scores released by the school board last week.

The nationally administered test measures both achievement and ability. In achievement, the first four grades' average scores also were generally at or slightly above national averages, the tests showed, while fifth through eighth grade average scores tended to be well below the national average. However, average scores for all of the classes, except the fourth grade, were below the national average in ability.

Donald E. Dearborn, assistant superintendent for curriculum, said the results from the spring testing showed that "students are working at their ability level. The staff is pleased with the results - that doesn't mean we are satisfied."

Alexandria second graders on the average produced the highest single test results released. The average class scores were in the 60th percentile for both language arts and math test, a 10 percentile increase in language arts and an 8 percentile increase in math scores over second graders' scores five years ago. A score in the 60th percentile means that the test results were higher than 60 percent of the students who took it nationwide. The class averaged in the 50th percentile in reading scores, an 8 percentile increase over average scores five years ago.

The second grade also showed major increases in its own scores over last year. The average scores rose in reading from the 39th to the 50th percentile, in language arts from the 46th to the 60th percentile, and in math from the 52nd to the 60th percentile.

Other grades ranked this way on their average scores.

First Grade - The class composite score, which included individual reading, language arts and math test results, was in the 48th percentile. The class also raised its language arts test result to the 49th percentile, a 7 percetile increase over Alexandria first graders five years ago. School officials said that a change of five or less in percentile ranking is considered insignificant.

Third Grade - Average scores showed some general improvement through their school career. Since first grade, the average class scores have risen in reading from the 40th to the 57th percentile and in language arts from the 49th to the 59th percentile. The class average, however, fell to the 48th percentile in math from the 63rd percentile last year and the 55th percentile ranking it held while in first grade.

Compared to third graders's average scores five years ago the class had a 10 percentile increase in reading, a 15 percentile increase in language arts and a 10 percentile increase in math.

Fourth Grade - Class average scores have risen in reading from the 37th to the 57th percentile and in language arts from the 44th to the 55th percentile since they started school. The average ability level has also risen from the 41st percentile to the 52nd. Compared to the fourth grade class five years ago, the current class averaged in reading an 11 percentile increase, in language arts an 8 percentile increase, in math a 12 percentile increase and in social studies a 7 percentile increase.

Fifth Grade - The class average math score was in the 46th percentile, compared to the 34th percentile for the average fifth grade score five years ago. The class reading score fell from the 51st to the 45th percentile in the last year, but it was still higher than the class's ranking when they were first graders - in the 37th percentile. The class average also fell, however, from the 49th percentile in social studies testing last year to the 40th percentile.

Sixth Grade - Class scores showed a marked decline over scores from sixth graders five years ago - from the 44th to the 34th percentile in ability levels, 46th to the 36th percentile in reading, from the 49th to the 42nd percentile in language arts, from the 43rd to the 35th percentile in social studies and from the 43rd to the 37th percentile in science.

The class also has been showing a fairly steady decline in average test results since it was tested in second grade. Ability scores have fallen from the 40th to the 34th percentile. Achievement test results have fallen from the 42nd to the 36th percentile in reading, from the 50th to the 42nd percentile in language arts and from the 52nd to the 38th percentile in math. The class scores also dropped in the last two years from the 45th to the 35th percentile in social studies.

Seventh Grade - Class averages declined in comparison with the scores of seventh graders five years ago - from the 42nd to the 36th percentile in reading and the 42nd to the 34th percentile in social studies. Since the class was in third grade its average ability test results have fallen from 43rd to the 32nd percentile. Average achievement test results have also fallen from the 47th to the 36th percentile in reading since the class was in third grade. Since fourth grade the class's average has dropped on social studies tests from the 45th to the 34th percentile and on science tests from the 47th to the 35th percentile. Since last year, the class average has fallen from the 43rd to the 36th percentile in reading, 47th to 40th percentile in language arts, 43rd to 36th percentile in math, 45th to 34th percentile in social studies and 42nd to 35th percentile in science.

Eighth Grade - Average results for the class have remained fairly constant over the last five years, but this year's class dropped from the 48th to the 40th percentile in average reading scores since it was in fourth grade.