When teacher Dorothy Porter asked her second graders this week to identify some words that had the long "i" sound, Jennifer, a peanut of a child in a baby doll top and blue-jeans, shot up her hand. "Fish," she answered.

"No, darling, that's our word for our short i sound," Porter said. "Do you have a word with a long i sound?" The child sadly shook her head no.

Promoted from first grade because of her age and not her skills, still learning to write her ABC's while others learn compound words, and still counting on her fingers, Jennifer is one of 10,646 District of Columbia first, second and third graders who will not be promoted to the next grade level this semester. She and the others did not master enough skills in reading or math or both under the school system's new promotion plan.

School officials disagree on the reasons Jennifer and the others are failing, but her daily struggle illustrates what life is like for half of the 21,622 primary grade students in city public schools.

Jennifer's problems are typical of what teachers have encountered as they try to ensure that students are not promoted to the next grade unless they know how to read, write and compute math problems accordingly. Under the so-called Pupil Progress Plan, which specifies what skills each student must learn at each grade level, the ability to recognize short and long vowel sounds is considered "critical" -- a skill that second graders must have to advance from the fall semester to the spring semester.

When she entered the second grade at Bruce-Monroe Elementary on Georgia Avenue NW in the Columbia Heights neighborhood, her word-recognition level and math ability were below that of a first grader, according to her school record. Though she had been promoted to the second grade, she had yet to learn first-grade work.

The problems that Bruce-Monroe students are having with the promotion plan are common to students in other D.C. public schools as well. School system officials acknowledge that there are many more students like Jennifer, especially third graders, who did not learn enough in previous grades. As a result, their deficiencies are showing up now that they are expected to demonstrate their skills regularly in the classroom and on more frequent tests. This is one of the major reasons the officials cite for the large number of failing students.

"Some students are just slow," Porter says. "Some may have emotional, psychological or physical problems that are preventing them from learning."

School system officials insist, however, that under the new promotions plan, all students, no matter how slow, eventually will be able to master the required skills because they will be given extra help and extra time -- an extra semester, an extra year, if need be.

But these officials now face the massive task of bringing thousands of students such as Jennifer (not her real name) up to her grade level before the end of the year, in effect doing more than one semester's work between now and the close of the school year in June. Because of a lack of teachers, most of these students will stay with their same classroom teacher, who will be responsible for seeing that they master the necessary skills.

Throughout the city, 6,340 students in grades one through three -- the only grades where the plan is in effect -- were unable to master the required skills in both reading and math. An additional 4,306 failed in reading or math.

In Porter's second grade class, five of the 27 pupils failed to master the skills. In reading, they had problems learning to recognize suffixes and comprehend analogies, such as being able to observe that the eye is to the face as the toe is to the foot, Porter said. In math, her students cannot seem to master subtracting numbers where it is necessary to borrow 10 to complete the problem.

Mark is one such student. He works well when Porter is standing over him.

He can recognize words and add, although he has yet to master subtraction. But when Porter is not working with him directly, he wanders around the room, sucking his finger or talking to himself and his other classmates.

For the other students in Porter's class, the promotions standards are a cinch. One student, Flora, completes her classroom assignments and goes beyond them. In one assignment last week, she split compound words into two syllables and then immediately, on her own, began writing the words she had just learned in sentences.

But systemwide, the failing students mostly have had problems with reading comprehension -- understanding the main idea of a story and distinguishing fact from fiction.

In Jennifer's case, learning the vowels sounds is a baby step toward vocabulary building in the long road to learning to read. But Jennifer is still fairly far from being able to read much.

On one recent morning, while the other students were copying such compound words as "afternoon" and "barnyard," which Porter had directed them to split into two words, Jennifer sat writing her ABC's in capitals and small letters. That is how far behind she is.

In a typical language lesson, in which Porter has groups of students take their tiny plastic chairs and sit around her at the blackboard, Porter points to the word "tot," which has a short "o" sound and asks Jennifer to say the word. She put her tiny hand to her chin, crinkled her eyebrows and struck a thoughtful pose. "Two," she replied.

Because of its high enrollment, Bruce-Monroe received an extra teacher at the end of the first semester in January. Principal Alma Felder created a combination grade for second grade students who passed from level 2A to 2B and for third graders who did not pass level 3A.

Classes like this one are likely to become fairly common under the Pupil Progress Plan. Though most of the second-graders in the class are working at or near the proper grade level, many of the third-graders are still doing only first grade work and must be brought up two grades. Students in the new class range from 7 to 10 years old.

After the midsemester evaluation, Porter decided she needed to spend more time teaching reading and math and cutting the very rudimentary lessons she had been giving in science and social studies.

She also rearranged the tables and chairs in the class so that the better students can sit next to slower ones to help tutor them. Many of the children already leave the classroom for two 45-minute periods a day to get extra help in smaller classes from special reading and math teachers.

Felder said she has asked her music and art teachers to include reading and math exercises in their subject areas whenever possible. The other day, music teacher Francis Ball gave students a music and vocabulary building exercise by teaching them a song in which the youngsters had to find their own rhyming words for the song.

And they even learned a new song called "How Do You Spell Hippopotamus?"