The Alexandria School Board resolved a year-old controversy last week by adopting a new rule on how to determine class rank.

The rule is designed to prevent more than one student from finishing first in a graduating class, and to address an inequity in the old way of determining class rank. Six students will finish first in the class of 1985, according to James McClure of the T.C. Williams High School guidance department.

"I hope this [decision] clears up a very confusing mess, but since I didn't understand it from the start, I don't know if we have," admitted School Board Chairman Lou Cook, adding, "I think the Miss America contest is a lot easier to figure out."

The controversy arose last year when the parents of the student ranked first in the junior class told McClure their child would be taking more classes than the second-ranked student. Because grade-point averages in Alexandria are computed by dividing the number of quality points earned by the number of classes taken, their child's average would drop below that of the student ranked second if both made straight As this year.

As a stopgap measure, McClure last June persuaded the School Board to allow any student who ended this year with a 4.0 or better average to be ranked number one. (Because certain honors and advanced classes in Alexandria are weighted with an extra half point, it is possible to finish with an average higher than 4.0.)

Under the new rule, grades received in honors and advanced placement classes will continue to receive the extra half-point weight. Grade-point averages will continue to be computed by dividing the number of quality points achieved by the number of classes taken. The rule calls for the student with the highest average to be ranked first. If two or more students finish with a 4.0 or higher average, the following procedure will be used to determine the final rank:

* The student with the highest percentage of As will be ranked first.

T* If the tie remains unbroken, the student with the greatest number of classes taken will be ranked first.

* All students still tied will be ranked first. All students who remain in a tie for first will receive the title "valedictorian."

Likening class rank to a horse race, board member Timothy S. Elliott had recommended last month that the student who finished immediately behind the tied number ones be ranked number two, rather than, taking this year as an example, number seven. McClure was among those strongly opposed to this move. "Every person has to be accounted for," he says "if you don't [account for everyone] you're dishonest."

More than 100 places out of the approximately 800 in this year's T.C. Williams graduating class would disappear from the ranking if ties all the way down the line kept pulling students up from the bottom. Under such a system, the last student in a class of 800 could conceivably finish number 700.

McClure expects first-place ties to "happen very rarely," noting that this year is the first time he has seen the problem.

While doing their best to eliminate first-place ties for students in the Class of 1986, the board also moved to keep them from graduating on Friday the 13th by changing the proposed 1985-86 school calendar.

As always, there are 180 student days scheduled on the calendar, which has been amended to change the last day for students from Friday, June 13, to Thursday, June 12.

This was accomplished by eliminating Veterans Day as a student holiday, boosting the number of snow days on the calendar to three.

The change was opposed by board members Elliott, Nelson E. Greene Jr. and Lynwood G. Campbell Jr.