Parents at a Middlesbrough primary school have been sent a letter from the head teacher advising them on correcting their children's Teesside accents.
Pupils at Sacred Heart Primary School have been sent home with a list of 11 words or phrases which can cause problems with grammar or pronunciation.
Head teacher Carol Walker has placed the word "Yous" firmly in detention, explaining "the word you is NEVER a plural."
Mrs Walker, born in Stockton and head at the urban primary for 12 years, stressed the aim was not to wipe out the Teesside accent but to teach children standard English.
She wanted pupils to avoid being at a disadvantage in later life, especially in the jobs market, where those who cannot communicate clearly can struggle.
To back up efforts at school, she decided to write to parents asking for their help at home, and the response has been "really positive".
"We have not had any negative reaction at all.
It's about knowing when it is appropriate to use one voice rather than another.
I am not asking children to deny where they come from, I am saying to them there are certain situations where they need to be able to use standard English."
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