In the education systems of England, Northern Ireland, Wales, and some other Commonwealth countries, sixth form represents 2 years of post-GCSE academic education, where students (aged between 16 and 17 years of age by 31st August) prepare for their A-level (or equivalent) examinations.
In England, Wales, and Northern Ireland, the term Key Stage 5 has the same meaning.
The term sixth form describes the school years numbered 12 and 13, which are called the Lower Sixth (L6) and Upper Sixth (U6) by many schools, Students aged 16 or 17 by August 31st.
The term survives from an earlier system when the first five years of English secondary schooling were known as forms (which would originally have been long backless benches on which rows of pupils sat in the classroom). Pupils started their first year of secondary school in the first form or first year, and this was the academic year in which pupils would normally be 11 years old by August 31st. Pupils would move up a form each year before entering the fifth form in the academic year in which they would be 15 year olds by August 31st. Those who stayed on at school to study for A-levels moved up into the sixth form, which was divided into the Lower Sixth and the Upper Sixth. In some private schools, the term Middle Sixth was used in place of Upper Sixth, with the latter being used for those who stayed on for an extra term to take the entrance examinations that were previously set for candidates to Oxford or Cambridge universities. Other schools described these Oxbridge examination students as being in the Seventh Form or Third Year Sixth.
The system was changed for the 1990-1991 academic year and school years are now numbered consecutively from primary school onwards. Year 1 is the first year of primary school after Reception. The first year of secondary school (the old first form) is now known as Year 7. The Lower Sixth is now Year 12 and the Upper Sixth is Year 13. However, the term "Sixth Form" has still been retained as a vestige of the old system and is used as a collective term for Years 12 and 13. Public (fee-charging) schools, along with some state schools, tend to use the old system of numbering.
In some parts of the country, specialist sixth form colleges were introduced. A large proportion of English secondary schools no longer have an integral sixth form. This is mainly related to reforms in the later 20th century, where different political areas became a factor in the introduction of colleges instead of the original sixth forms. There are now numerous sixth form colleges throughout England and Wales, and in areas without these, sixth form schools and specialist further education (FE) colleges called tertiary colleges may fill the same role.
Sixth form is not compulsory in England and Wales (although from 2013 onwards, people of sixth form age must remain in some form of education or training in England only; the school leaving age remains 16 in Wales); however, university entrance normally requires at least three A2-level qualifications and perhaps one AS-level. Students usually select between three and five subjects from the GCSEs they have just taken, for one "AS" year, the AS exams being taken at the end of Lower Sixth. Three subjects are then carried into the A2 year (the dropped AS being "cashed in" as a qualification) and further exams are taken at the end of that year. The marks attained in both sets of exams are converted into UCAS points, which must meet the offer made by the student's chosen university.
In Northern Ireland, the equivalent of Reception is "P1", and the equivalent of the English Year 1 "P2", while the first year of secondary school is known as Year 8 or first year (rather than Year 7 as in England), and following that Lower and Upper Sixth are Year 13 and Year 14 respectively.
In the Scottish education system, the final year of school is known as Sixth Year or S6. During this year, students typically study Advanced Higher and/or Higher courses in a wide range of subjects, taking SQA exams at the end of both S5 and S6. Pupils in Scotland may leave once they have reached the age of 16; those who reach 16 before 30 September may leave after national examinations in May, whilst those who are 16 by the end of February may leave the previous Christmas.
It is not essential for candidates to do a sixth year if they wish to attend a Scottish university, as they have obtained adequate Higher grades in S5 and may apply and receive acceptance, though this is conditional on being successful in the examinations. However, the vast majority of Scottish students return for S6 if they plan to attend university. Some English universities will also accept Scottish students who have obtained adequate Higher grades in S5. It was announced in December 2008 that, as from 2010, UCAS will increase the number of points awarded to those who achieve Highers and Advanced Highers.
In some cases, particularly in independent schools, the term sixth form is also used for the last two years of secondary education.
Similarly, the term sixth form is also used to define the final two years of education before entering university in Malta.
In Malaysia, a sixth form is known as "Tingkatan 6," and lasts for three semesters.
In Singapore, however, the equivalent of a sixth form college would be called a junior college, where pupils take their Cambridge GCE A-levels after two years. Prior to the 1990s, these two years were known as "Pre-University" (Pre-U) 1 and 2.
In New Zealand, under the old system of forms, standards and juniors, sixth form was the equivalent of Year 12 in today's system. Year 13 was known as seventh form. Australia also sometimes uses the term for year 12, though the Australian year 12 is equivalent to the NZ Year 13 / seventh form and the UK's upper sixth / Year 13.
In Brunei, sixth form comprises Year 12 and 13, which may also be referred to as Lower and Upper Six. At the end of the schooling, students sit for Brunei-Cambridge GCE A Level. Students may also opt to take Advanced Subsidiary Level or AS Level halfway at the end of Lower Six or halfway through Upper Six. Sixth form is not compulsory, but a preferable choice for students wishing to continue in academic studies leading to university level.
In some college preparatory schools in the United States, such as The Hill School, Woodberry Forest School, Ethical Culture Fieldston School, Kent School, Pomfret School, The Church Farm School, The Haverford School, Portsmouth Abbey School and more, sixth form refers to the final year of education prior to college. It is the equivalent of twelfth grade in the US education system.