sixth form

Meanings

1. The final two years of secondary education, during which students of about 16 to 18 years of age prepare for their A-level examinations or equivalent qualifications.
2. a sixth form college.

Etymology

Earlier educational naming conventions in public schools termed every two years of education "forms" (itself sometimes said to be from form (“bench”), where students of certain ages would sit together, though disputed, or alternatively from form (“established method of expression or practice”)), where Years 12 and 13 (i.e. ages 16 to 18) was the "sixth" and final form. State schools adopted the term "sixth form" and retained it when the rest of the form structure was dropped.