"How many of you have learned your ABC's?" The teacher asked the small group of students before her.

The eight 6th- and 7th-graders all raised their hands.

"And how many of you have learned your LMNOP's?" No response. "That's what I'm going to be teaching you--your LMNOP's."

The classroom is in the Rockville offices of Specific Diagnostics, a 10-year-old company specializing in the testing and tutoring of people with learning differences and difficulties.

"We all have different ways or styles of learning," explains Lynn O'Brien, founding director of the company. "Many of the people we work with have diagnosed learning disabilities.

"But over the years, we have tested large numbers of people of all ages for suspected learning problems and found none. What we've discovered are people who simply don't know how to learn."

Consequently, three years ago O'Brien began developing and offering a course called "SOS," for Strengthening of Skills.

" 'SOS' is also a well-known distress signal, so the name is rather appropriate when you see the despair of students and their parents who know something is wrong with their school performance, but they don't know what. We have designed a course for people to discover their own learning style, their assets and their liabilities."

"Each child sitting in the classroom will be different," says Dr. Larry Silver, deputy director of the National Institutes of Mental Health and an expert on youth and learning problems. "What we and O'Brien are basically saying is:

Given your particular nervous system--here's the best way for you to learn. You've got visual strengths and auditory weaknesses so you're going to have to learn with your eyes. Your ears are going to mess you up. Or, you've got auditory strengths, so you're going to learn through your ears; your eyes are going to mess you up. Let me tell you how to do that."

O'Brien and her staff have taught and are teaching the SOS course both to the public and several area schools: Among them, St. Anselm's, Holy Trinity, St. Bartholomew's, the Field School and Georgetown Preparatory School, where it is a required course for freshman.

SOS is divided into two six-week courses for different age groups: grades 5-8 and 9-12.

"The pre- and post-course testing are extremely important," says O'Brien. "It shows us and students how they best take in information, store it and express it. We always find they had no idea at all how they could best learn."

The "LMNOP's"? The letters stand for Listening, Memory, Notetaking, Outlining and Planning (or scheduling): the fundamental areas that underlie all learning tasks.

Although O'Brien acknowledges that students may get a poor-quality teacher at one time or another, "If they are secure with their own learning abilities and skills, the odds are they'll succeed in the course and learn something despite that teacher.

"It's important for them to see how they are alike. It makes it 'okay' for them to have a problem if it isn't theirs alone. We constantly emphasize that differences in people are natural and acceptable, not bad."

Specific Diagnostics, 11600 Nebel St., Rockville. 468-6616. Cost of 18-hour SOS course: $120.