The stages are as follows:
|Key Stages (KS)||Ages||Duration||Years groups (Y)||Forms||Final exams|
|0||4–5||2 years (1 compulsory)||Nursery, Reception||Nursery, Infant Reception Class|
|KS1||6–7||2 year groups||Year 1 to 2||1st–2nd form infants||KS1 SATS, Phonics and Reading Check (taken in Year 1 but may be retaken if failed in Year 2)|
|KS2||8–11||4 year groups||Year 3 to 6||1st–4th form juniors||SATS Tests, eleven plus exam (generally only for Grammar school entry)|
|KS3||12–14||3 year groups||Year 7 to 9||Secondary|
|KS4||15–16||2 year groups||Year 10 to 11||Secondary||GCSEs|
|KS5||17–19||3 year groups||Year 12 to 14||Sixth form||A-Levels, AS-Levels, NVQs, National Diplomas|
The National Curriculum sets out targets to be achieved in various subject areas at each of the Key Stages.
The Key Stages were first defined in the 1988 Education Reform Act to accompany the first introduction of the National Curriculum. The precise definition of each of the main 4 Key Stages is age-related, incorporating all pupils of a particular age at the beginning of each academic year. The Key Stages were designed to fit with the most prevalent structures which had already grown up in the education system over the previous 100 years of development.
Prior to the four main key stages, pupils attend a Foundation Stage, the latter part of which is compulsory.
Key Stage 1 fits broadly with the first stage of primary education, often known as infant schools. This break had existed for some time, being acknowledged in the 1931 Hadow report as 'axiomatic' by as early as 1870.
Secondary education was split between KS3 and KS4 at age 14 to align with long-existing two-year examination courses at GCSE level.