Almost two-thirds of the more than 10,600 D.C. public school elementary students who failed last semester under a new, stricter promotion standard at midyear will be promoted to the next grade level based on their performance during the second semester that ends this month, Acting Superintendent James T. Guines announced yesterday.

Based on projections from all the city's elementary schools, 3,857 pupils in grades one through three -- the only grades covered by the new standard -- have failed to master skills in reading and math and will not be promoted

Guines said 826 other elementary pupils, who failed either reading or math but not both, will be promoted along with the successful students but probably will be given "transitional" instruction for the work they failed to learn.

At the beginning of the school year, the District introduced midyear reading and math promotion standards for the three elementary grades and more than half of the 21,000 students involved failed one or both of them. About 6,300 failed both reading and math and about 4,300 failed one or the other.

Guines, who once criticized the new promotions plan as unnecessarily punitive toward students, said the second semester results "demonstrate to me that this plan works." He added that the system will go ahead with plans to introduce stiffer promotion standards in grades four through six next September.

The number of students Guines said would be retained this year is about 1,200 more than the number of pupils retained last year in those three grades.

Guines said school officials expected a larger number of retentions this year since there were no specific standards for promotion in prior years. He said teachers often moved students on because of their age rather than their achievement.

School officials attributed this semester's lower number of failures to the additional help the students received from their classroom teachers, special Title I reading and math teachers and tutoring from citizen volunteers.

"What it came down to was accountability -- the parents, teachers, and principals knowing what's expected of them," said Dolores Zucker, principal of Amidon Elementary School in Southwest.

Zucker added that pupils frequently do better in the last half of the year since much of the second semester work builds on what the students learned in the first half of the year. Several students at Amidon, she said, made up a full year's work in the second semester.

Under the promotion plan, officially called the "pupil progress plan, teachers have a checklist of skills for each grade. It includes identifying consonants and vowels and adding and subtracting three-digit numbers for the second grade. The teacher must certify through written classroom work and a variety of tests that the students have mastered the skills. But the teacher remains the final judge of whether a student passes.

William Lipscomb, principal of Merritt Elementary in far Northeast, said teachers grew accustomed to teaching by the plan during the second semester. He also said some students were penalized for not mastering a skill that their teachers had not had time to teach them.

When so many youngsters failed last semester, especially in the third grade, school officials said a large part of the problem was that pupils had not learned first and second grade work. Even greater numbers of students in the fourth, fifth and sixth grades are expected to fail when the stiffer standards go into effect in those grades next semester.