The O Levels and A Levels system is also used in Singapore. This is not surprising considering that the education system is also largely based on the British one. While Britain has done away with the O Levels and replaced it with the GCSE, Singapore has still retained the O Levels, and is probably the only country in the world to do so.
The O levels (O = ordinary) exam is taken at the end of secondary school education, as some Dopers have already pointed out, which is around the age of 16. All candidates sit for papers set by the Cambridge folks, specifically their Local Examinations Syndicate, which bases the papers on the local syllabus. However, the Ministry of Education sets the Mother Tongue papers (ie in Malay, Tamil, Chinese).
Examples of O Level papers are:
History (Southeast Asian)
History (post 1917 - 1990)
Geography
Literature (English, Chinese, the latter taken in Chinese, of course)
English Language
Mathematics
Chemistry
Physics
Biology
All candidates sit for at least 6 papers, English, Math, and 4 more subjects of their own choice. The grades of these 6 papers constitute the L1R5 – 1 Language, 5 Relevant subjects – which is needed for Junior College (a High School/College sort of institution) entrance. It is in Junior College where students sit for their A Levels papers.
There students will choose to focus in major areas namely Science or Arts. Science stream students will do the sciences (d’oh) like Biology, Chemistry, Physics etc. Arts students do literature, history, geography, economics etc.
These subjects, taken at A level, are crucial for entrance to local universities.
Other papers, like the General Paper (something like critical analysis of current affairs) and Mother Tongue, are Singapore-specific but just as important for university entrance as the A levels.