Secondary education or post-primary education covers two phases on the International Standard Classification of Education scale: Level 2 (lower secondary education, less commonly junior secondary education) is the second and final phase of basic education, and Level 3 (upper secondary education or senior secondary education) is the phase immediately preceding tertiary education. Every country aims to provide basic education, but systems and terminology remain unique to each country. Secondary education typically takes place after six years of primary education and is followed by higher education, vocational education or employment. In most countries secondary education is compulsory, at least until the age of 16. Children typically enter the lower secondary phase around age 12. Compulsory education sometimes extends to age 20 and further.

Since 1989, education has been seen as a basic human right for a child; Article 28 of the Convention on the Rights of the Child states that primary education should be free and compulsory while different forms of secondary education, including general and vocational education, should be available and accessible to every child. The terminology has proved difficult, and no universal definition existed before ISCED divided the period between primary education and university into junior secondary education and upper secondary education.

In classical and medieval times, secondary education was provided by the church for the sons of nobility and to boys preparing for universities and the priesthood. As trade required navigational and scientific skills, the church expanded the curriculum and broadened enrollment. With the Reformation the state began taking control of learning from the church, and with Comenius and John Locke education changed from being repetition of Latin text to building up knowledge in the child. Education was for the few. Until the mid-19th century, secondary schools were organised to meet the needs of different social classes, with the labouring classes getting four years, the merchant class five years, and the elite getting seven years. The right to secondary education was codified after 1945, and some countries are moving toward mandatory, free secondary education for all youth under 19.

Definition Secondary education refers to the stage of formal education that follows primary education and precedes higher education. It is typically offered to students between the ages of 12 and 18, although the specific age range may vary depending on the educational system and country. Secondary education aims to provide students with a well-rounded education that prepares them for higher education or the workforce. It aims to develop their intellectual, social, and emotional skills, while also fostering critical thinking, creativity, and independence.

The 1997 International Standard Classification of Education (ISCED) describes seven levels used to compare education internationally. Within a country, these can be implemented in different ways, with different age levels and local denominations. The seven levels are: Pre-primary education Primary education or first stage of basic education Lower secondary or second stage of basic education (Upper) secondary education Post-secondary non-tertiary education First stage of tertiary education Second stage of tertiary education

Within this system, Levels 1 and 2 – primary education and lower secondary, respectively – together form basic education. Beyond that, national governments may attach the label of secondary education to Levels 2 through 4 together, Levels 2 and 3 together, or Level 2 alone. These level definitions were created for statistical purposes and to allow the collection of comparative data nationally and internationally. They were approved by the UNESCO General Conference at its 29th session in November 1997. Though they may be dated, they do provide a universal set of definitions and remain unchanged in the 2011 update.

The start of lower secondary education is characterised by the transition from a single-class teacher delivering all content to a cohort of pupils to one in which content is delivered by a series of subject specialists. Its educational aim is to complete provision of basic education (thereby completing the delivery of basic skills) and to lay the foundations for lifelong learning.

Lower secondary education is likely to show these criteria: entry after some six years of primary education the requirement for more highly qualified teachers teaching only within their specialism exit to Level 3 courses, or vocational education, or employment after nine or more total years of education.

The end of lower secondary education often coincides with the end of compulsory education in countries where that exists.

(Upper) secondary education begins after completing basic education, which is also defined as completing lower secondary education. The educational focus is varied according to the student's interests and future direction. Education at this level is usually voluntary.

(Upper) secondary education is likely to show these criteria: entry after some nine years of basic education typical age at entry is between 14 and 16 years all teachers have level 5 qualifications in the subject they are teaching exit to Level 4 or 5 courses or to direct employment.

More subjects may be dropped, and increased specialism occurs. Completion of (upper) secondary education provides the entry requirements to Level 5 tertiary education, the entry requirements to technical or vocational education (Level 4, non-tertiary course), or direct entry into the workplace.

In 2012, the ISCED published further work on education levels, codifying particular paths and redefining the tertiary levels. Lower secondary education and (upper) secondary education could last between two and five years, and the transition between the two often would be when students were allowed some subject choice.

Terminology around secondary education systems varies by country. Secondary schools may also be called academies, colleges, gymnasiums, high schools, lyceums, middle schools, preparatory schools, sixth-form colleges, upper schools, or vocational schools, among other names. For further information about these terms and their definitions, see the section below, organised by country.

History

A form of education for adolescents became necessary in all societies that had an alphabet and engaged in commerce. In Western Europe, formal secondary education can be traced back to the [can be traced back to the educational practices of ancient Athens. Though their civilisation was eclipsed and they were enslaved, Hellenistic Athenian teachers were valued in the Roman system. The Roman and Hellenistic schools of rhetoric taught the seven liberal arts and sciences – grammar, rhetoric, logic, arithmetic, geometry, music and astronomy – which were regarded as a preparation for the study at a tertiary level of theology, law and medicine. Private tutors at home prepared boys to enter these schools. Girls received tuition only at home.

England provides a good case study. When Augustine of Canterbury brought Christianity there in 597, no schools existed. He needed trained priests to conduct church services and boys to sing in the choir. He had to create both grammar schools that taught Latin, enabling the English to study for the priesthood, and song schools (choir schools) that trained the 'sons of gentlefolk' to sing in cathedral choirs. In the case of Canterbury (597) and Rochester (604), both still exist. Bede in his Ecclesiastical History of the English People (732) tells that the Canterbury school taught more than the 'intended reading and understanding of Latin', but 'the rules of metric, astronomy and the computus as well as the works of the saints'. Even at this stage, tension remained, as the church worried that knowledge of Latin would give students access to non-Christian texts it did not want them to read.

Over the centuries leading to the renaissance and reformation, the church was the main provider of secondary education. Various invasions and schisms within the controlling church challenged the focus of the schools, and the curriculum and language of instruction waxed and waned. From 1100, with the growth of the towns, grammar schools 'free' of the church were founded, and some church grammar schools were handed over to the laïty. Universities were founded that did not just train students for the priesthood.

Renaissance and Reformation Whereas in mainland Europe the Renaissance preceded the Reformation, local conditions in England caused the Reformation to come first. The Reformation was about, among other things, allowing the laïty to interpret the Bible in their own way without priestly intervention, preferably in the vernacular. This stimulated the foundation of free grammar schools - who searched for a less constrained curriculum. Colonisation required navigation, mensuration, languages and administrative skills. The laïty wanted these taught to their sons. After Gutenberg in 1455 had mastered moveable metal type printing and Tyndale had translated the Bible into English (1525),. Latin became a skill reserved for the catholic church and sons of conservative nobility. Schools started to be set up for the sons of merchants in Europe and the colonies too- for example Boston Latin Grammar School (1635).

Comenius (1592–1670),Daniel Murphy, Comenius: A Critical Reassessment of his Life and Works (1995), p. 8 and p. 43. a Moravian protestant proposed a new model of education- where ideas were developed from the familiar to the theoretical rather than through repetition, where languages were taught in the vernacular and supported universal education. In his Didactica Magna (Great Didactic), he outlined a system of schools that is the exact counterpart of many western school systems: kindergarten, elementary school, secondary school, six-form college, university. Locke's Some Thoughts Concerning Education (1693) stressed the importance of a broader intellectual training, moral development and physical hardening.

The grammar schools of the period can be categorised in three groups: the nine leading schools, seven of them boarding institutions which maintained the traditional curriculum of the classics, and mostly served 'the aristocracy and the squirearchy'; most of the old endowed grammar schools serving a broad social base in their immediate localities which also stuck to the old curriculum; the grammar schools situated in the larger cities, serving the families of merchants and tradesmen who embraced change.

Industrialisation During the 18th century their social base widened and their curriculum developed, particularly in mathematics and the natural sciences. But this was not universal education and was self-selecting by wealth. The industrial revolution changed that. Industry required an educated workforce where all workers needed to have completed a basic education. In France, Louis XIV, wrestled the control of education from the Jesuits, Condorcet set up Collèges for universal lower secondary education throughout the country, then Napoleon set up a regulated system of Lycee. In England, Robert Peel's Factory Act 1802 required an employer to provide instruction in reading, writing and arithmetic during at least the first four years of the seven years of apprenticeship. The state had accepted responsibility for the basic education of the poor. The provision of school places remained inadequate, so an Order in Council dated 10 April 1839 created the Committee of the Privy Council on Education.

Universal education