Key Stage 1 is the legal term for the two years of schooling in maintained schools in England and Wales normally known as Year 1 and Year 2, when pupils are aged between 5 and 7. This Key Stage normally covers pupils during infant school, although in some cases this might form part of a first or primary school. It is also the label used for the third and fourth years of primary education in Northern Ireland. In Hong Kong, it is used to describe Primary One to Primary Three.
England and Wales
The term is defined in the Education Act 2002 as "the period beginning at the same time as the school year in which he attains the age of six and ending at the same time as the school year in which the majority of pupils in his class attain the age of seven"
The term is used to define the group of pupils who must follow the relevant programmes of study from the National Curriculum. All pupils in this Key Stage must follow a programme of education in at least 10 statutory areas :