<P> As with primary schools, students pass from grade to grade regardless of knowledge or academic achievement, the result being that classes often have students of vastly differing abilities learning the same subject material together . In the final year of middle school examination scores become very important for the top students hoping to gain entrance into the top high schools, and for those in the middle hoping to get into an academic rather than a technical or vocational high school . Otherwise, examinations and marks only matter insofar as living up to a self - enforced concept of position in the school ranking system . There are some standardized examinations for certain subjects, and teachers of academic subjects are expected to follow approved textbooks, but generally middle school teachers have more flexibility over curricula and methods than teachers at high school . </P> <P> More than 95% of the middle school students also attend independent owned, after - school tutoring agencies known as hagwon, and many receive extra instruction from private tutors . The core subjects, especially the cumulative subjects of Korean, English and math, receive the most emphasis . Some hagwon specializing in just one subject, and others offer all core subjects, constituting a second round of schooling every day for their pupils . Indeed, some parents place more stress on their children's hagwon studies than their public school studies . Additionally, many students attend academies for things such as martial arts or music . The result of all this is that many middle school students, like their high school counterparts, return from a day of schooling well after sunset . The average South Korean family spends 20% percent of its income on after - hours cram schools, more spending per capita on private tutoring than any other country . </P> <P> High schools in South Korea teach students for three years, from first grade (age 15 - 17) to third grade (age 17 - 19), and students commonly graduate at age 18 or 19 . High school students are commonly expected to study increasingly long hours each year moving toward graduation, to become competitive and be able to enter attractive universities, such as the top SKY (Seoul National, Korea, and Yonsei Universities). Many high school students wake and leave home in the morning at 5 a.m. and return home after studying well after 10 p.m., then return to specialty study schools often to 2 a.m., from Monday to Friday and also they often study on weekends . </P> <P> It is a commonly known saying in Korea that' If you sleep three hours a night, you may get into a top' SKY university;' If you sleep four hours each night, you may get into another university; if you sleep five or more hours each night, especially in your last year of high school, forget about getting into any university .' Accordingly, many high school students in their final year do not have any free time for holidays, birthdays or vacations before the CATs (National College Scholastic Aptitude Test, Korean: 수능), which are university entrance exams held by the Ministry of Education . Surprisingly, some high school students are offered chances to travel with family to enjoy fun and relaxing vacations, but these offers are often refused on the first suggestion by the students themselves, and increasingly on later additional trips if any, due to peer influences and a fear of' falling behind' in classes . Many high school students seem to prefer staying with friends and studying, rather than taking a break . The idea of' skipping classes' for fun is extremely rare in Korea . Rebellious students will often stay in class and use smart phones connected to the internet to chat with friends behind the teacher's back during classes . </P>

What age do you graduate high school in south korea