When Yoo moved from Yeosu, South Jeolla, to the ritzy Gangnam area of Seoul, she found herself lagging behind her peers in the second year of high school.

“In Gangnam, second-year students are already learning third-year material, so unless I get after-school tutorial or private classes, I would have no idea of what’s going on,” Yoo said. “And in that case, there is no point in attending school.” So she dropped out to study at home for a high school equivalency exam.

Having ranked tenth in her middle school in Yeosu, Yoo found “preparing for the qualification examinations were much more manageable than attending high schools in Gangnam where classes are really designed for the very top-ranking students.”

Yoo may have been right to quit. Gangnam schools are not great places for the mediocre, as an analysis by the JoongAng Ilbo proves.

For although it’s true that many students in Gangnam spend their days attending school and cram schools back-to-back to pave their way to top-tier universities and prestigious jobs, that’s not the entire picture according to the analysis.

According to an analysis conducted by the JoongAng Ilbo, which surveyed 24 high schools in Gangnam and 106 outside Seoul, schools in Gangnam do have the highest number of first rate students.

But schools outside of Seoul have the largest number of second-tier students.

The top 4 percent of students nationwide receive the top rating, and the upper 19 percent receive second and third ratings in the national college entrance exam. The ranking runs from one to nine.

Using Olympian standards, Gangnam wins the most gold. But schools outside of Seoul earn more silver and bronze.

That does mean Gangnam has the highest percentage of students who get into the so-called SKY schools - an acronym for the top three universities in South Korea: Seoul National, Korea, and Yonsei - while schools outside Seoul put more second and third-tier students into leading universities.

“High schools in Gangnam have a lot of top-ranking students, which creates an illusion that any student attending a school in Gangnam does well,” said Oh Jong-un, a director at Etoos, a private education group in Korea. “However, students in the high-middle ranks in Gangnam often don’t do as well as their counterparts outside of Seoul.”

Im Seong-ho, a representative of the Haneul education group, says that first-rate students frequently transfer to schools in Gangnam when they move up to middle school but, “on the other hand, there are cases where Gangnam-native students in the fourth to fifth tiers, move out of Gangnam to other areas.”

“In Gangnam, the number of admissions into SKY schools is the yardstick of a high school’s quality,” said a Gangnam high school math teacher who wished to remain anonymous. “So the entire system is geared towards nurturing first rate students.”

Im says that since Gangnam schools are focused on top-ranking students, they often fail to help fourth-to-sixth tier students move up in rankings. “In Gangnam, it is often the case that schools pour their attention into the top 2 percent of the top-ranking students, so you end up with a structure in which the majority of students are inevitably neglected.”

Another problem high schools in Gangnam face is a polarization of scores. In Korean, math and English, Gangnam has more students in the bottom 40% (sixth to ninth tiers) than schools outside of Seoul. The percentage of such low-ranking students in Korean is twice as high in Gangnam (25%), compared to schools outside of Seoul (12.2%).

“Some do get high scores in English but about a half to a third of the class could just about write the alphabet,” said a Gangnam high school English teacher. “Since scores are so extremely polarized, classes have no sense of coherency.”

He added that under normal circumstances, second-to-third rate students are considered elites but in Gangnam, only first-rate students enjoy such status. So well-performing students lose confidence and the will to compete at a higher level.

Another characteristic of schools in Gangnam is that students score better in English and math than their counterparts outside of Seoul, but don’t fare as well in Korean. The percentage of first-rate students in the Korean language is lower in Gangnam (8.9%) than in schools outside of Seoul (9.8%).

Han Ju-hui, the head of career development at Jungsan High School, said, “With English and math, it pays to have private classes or tutorials from early childhood. Results in aptitude tests certainly reflect this.”

Yu Mi-hwa, who teaches English at Apgujeong High School, added, “Since students in Gangnam have more opportunities to study English either abroad or in private lessons, they tend to do very well in English.”

To do well in Korean, according to Bae Yeong-jun, head of career development at Posung High School, tutoring doesn’t work. “It is a discipline centered around reading and comprehension, skills that can’t be cultivated by cramming.”

BY YOON SEOK-MAN [enational@joongang.co.kr]