Primary education
Primary school
Foundation Stage
Primary 1, age 4 to 5 (equivalent to Reception in England and Wales)
Primary 2, age 5 to 6
Key Stage 1
Primary 3, age 6 to 7
Primary 4, age 7 to 8
Key Stage 2
Primary 5, age 8 to 9
Primary 6, age 9 to 10
Primary 7, age 10 to 11
(For entry to grammar schools, entrance exams take place to determine places. The Eleven Plus no longer operates in Northern Ireland but schools still operate exams.)
Secondary education
Secondary school or grammar school
Key Stage 3
Year 8, age 11 to 12 (equivalent to Year 7 in England and Wales)
Year 9, age 12 to 13
Year 10, age 13 to 14
Key Stage 4
Year 11, age 14 to 15
Year 12, age 15 to 16 (GCSE examinations)
Secondary school, grammar school, or further education college
Sixth form
Year 13, age 16 to 17 (AS-level examinations)
Year 14, age 17 to 18 (A-levels (A2))
Note that although the Department of Education uses Year 8 to Year 14 for secondary education, the traditional First-Fifth Form, Lower Sixth and Upper Sixth are still used, at least informally, by some schools.