The connection between exams and the curriculum: The prevalence of testing and examinations has a long history and is embedded in the culture. The curriculum is effectively defined by what is examined. Places come to a standstill on days of public examinations such as the university entrance examination. Traffic is stopped and planes will be diverted to minimise noise.
The curriculum is dominated by languages, maths and science. English has become a very important element of social mobility.
The high scores on Pisa (held every three years by the Organisation for Economic Co-operation and Development to measure pupils' skills in reading, numeracy and science) probably reflects a strong overlap between the test questions and the exam-driven curriculum that schools focus on, as well as the hard work by the pupils and the strong support/pressure from parents to succeed. JAMB
The connection between social mobility and exams: South Korea, and other Far East countries, have a long history of using competitive public examinations as a vehicle for selection and social mobility. It only developed in the West in the 18th Century. Whether you get into a good school or university is wholly dependent on exam results. A child's future, status and social mobility are strongly connected to exam outcomes.
It results in very strong parental support or pressure, depending on how you look at it. When children go home the parents are often on top of them to do their homework. They will also employ private tutors if they can afford it.
The culture of diligence: Children are expected to put the time in. There's a belief that people have differing abilities but everyone can get there - it might just take some a lot longer.
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Although the classroom has become more interactive in the last 10 to 20 years, a South Korean lesson would be viewed by people in the UK as didactic, orderly and teacher-led.