The Welsh Not was a token used by teachers at some schools in Wales, mainly in the 19th century, to discourage children from speaking Welsh at school, by marking out those who were heard speaking the language. It could be followed by an additional punishment; sometimes a physical punishment. There is evidence of the Welsh Not's use from the end of 18th to the start of the 20th century, but it was most common in the early- to mid- 19th century.
The token was seen as a teaching aid to help children learn English. Over time, however, excluding Welsh began to be viewed as an ineffective way of teaching English and by the end of the 19th century schools were encouraged to use some Welsh in lessons. There was a widespread desire for children to learn English among Welsh people in the 19th century and the Welsh Not was not part of any government policy.