AN ALARMING number of Prince George's County public high school students will not be able to participate in extracurricular activities for the rest of the school year. It is the result of a major effort by Prince George's school officials to encourage hard work by allowing only those students with C averages or higher to participate in activities such as athletics, theatrical shows and clubs. The possible payoff: students will work harder and achieve higher grades. The possible cost: disillusionment among some students, who derive self-esteem from extracurricular activities.

Some 14,195 students (out of 36,197) failed to do at least C-level work last semester, and that is disturbing. The school system warned students about the requirement before school ended last year. It was outlined in a letter to parents, noted in the student handbook and announced during orientation last September. Some coaches even organized after-school study halls.

No doubt there were smiles and sighs of relief from students who had worked diligently, inching along to achieve the necessary 2.0. There also was discouragement, as well as interrupted plans, among the students who fell below the C standard.

An attempt to make students work harder certainly has merit. The number of gifted high school athletes that goes on to become millionaires in professional sports is minuscule. The stars of the high school play seldom go on to see their names on Broadway. Students must realize that getting a good education is an opportunity to be seized now, not years down the pike.

But there is something rather rigid about the Prince George's effort. It does not take into account the student who has improved since last semester but nevertheless failed to achieve a C average. Improvement of this kind certainly deserves some recognition. Nor does the policy take into account the possibility that a student may really apply himself early in the spring semester, pulling a B or even an A in the third grading period. This student is not eligible to return to extracurricular activities until the following fall. Finally, the policy downplays talents that are not academic. Sometimes these other talents do much for a person's sense of self-esteem. Sometimes they are the reason that a student comes to school every day.

It is laudable that the Prince George's County school system is serious about making students work harder, but the standard may be a bit too harsh on those who really are trying harder. The fact that 39 percent of the county's high school students failed to get at least a C average is not just a measuring stick that tells students they have much more work to do; it is telling administrators, teachers, counselors and parents that they must must work harder too.