Key Stage 2 is school years 3 to 6, ages 7 - 11. Junior school.

Key Stage 3 is school years 7 to 9, ages 11 - 14. Senior school

Key Stage 4 is school years 10 and 11, ages 14 - 16. GCSE

A-Level is school years 12 and 13, ages 16 - 18; or college, ages 16+.