The headteacher of a Black Country school has defended banning the local dialect from classrooms, saying it will help raise literacy standards.
John White said the school had decided to ban the dialect from lessons or otherwise put at risk the future prospects of its 600 pupils.
The measure, which came into force at Colley Lane Community Primary School in Halesowen at the start of the term, is accompanied by a guide explaining to parents the reasons for the ban.
Some mothers and fathers have reportedly criticised the step as an attack on Black Country culture.
However, Mr White said: "Some have thought it might be a bit finger-wagging or patronising, which we did not want to do and indeed we discussed that before we even introduced the ban."
The list of 10 banned words include prohibitions on saying 'you cor' rather than 'you can't'.
The Black Country area is made up of Walsall, Sandwell, Dudley and parts of Wolverhampton and is distinct from neighbouring Birmingham.
Other phrases on the banned list include the more widely-used 'somfink' instead of 'something'; 'gonna' rather than 'going' and 'ain't' rather than 'are not'.
Mr White said: "We'd been looking at our literacy standards and we wanted to talk to parents about some of the confusion that happens when children are talking in slang to their mates in the playground.
"When it comes to phonics and English lessons it can be very confusing for the children.
"When they are reading phonics, it's incorrect, so we think it's better for them this way."
He added teachers had spoken to colleagues at schools in Bradford and south London, where similar methods have been successfully employed.
The supporting booklet accompanying the ban is designed to get parents supporting the measure at home.
Mr White added he was seeing an increasing number of pupils coming through nursery with little or no proper English, and put slipping standards of language down in part to "a reduction of conversations around the dinner table" at home and too much time spent by children "in front of television screens".
"We're not stopping them talking to their friends in the playground how they want to," he added.
"We're just saying that in the classroom we'll correct them."
The headteacher said literacy was the school's "biggest challenge" with 40% of the intake on free school meals - a measure of how many disadvantaged pupils there are in a school - while a sizeable minority were from the local Yemeni community, whose first language is Arabic.
"This isn't an attack on local culture," added Mr White.
"The Black Country is a fantastic region with wonderful history and we're absolutely clear that this is not about damaging that in any way.
"It's about getting the best for our children, who when they leave here will be in competition with other young people for jobs, college and university places.
"We want to be able to prepare them in the best way possible for that."
He added he was glad the controversy around the ban had people talking, saying it was an important issue not only locally but nationally.