Welsh medium education should be distinguished from the teaching of the Welsh language itself as an academic subject. Welsh as a subject is taught as a first language in Welsh medium schools. In the majority of English medium schools, Welsh is taught as a second language and became compulsory for all pupils in Wales at Key Stages 1, 2 and 3 (up to age 14) in 1990. In 1999, it became a compulsory subject for Key Stage 4 pupils (GCSE (ages 15 and 16)). Provision of Welsh as a subject in independent (private) schools is less widespread -- only a few provide it, and it is taught as a second language. There is no private designated Welsh - medium school in Wales, although one does exist in London, known as the London Welsh School.
when did the welsh language became a core subject in the national curriculum in wales
1990