C1 Grammar schools: What are they and why are they controversial?

Grammar schools are state secondary schools that select their pupils by means of an examination taken by children at age 11, known as the "11-plus".

There are only about 163 grammar schools in England, out of some 3,000 state secondaries, and a further 69 grammar schools in Northern Ireland.

Under the grammar school system, pupils who pass the exam can go to the local grammar, while those who do not go to the local "secondary modern school".

http://www.bbc.com/news/education-34538222