Calling teachers "Sir" or "Miss" is depressing, sexist and gives women in schools a lower status than their male counterparts, an academic has said.
Prof Jennifer Coates told the Times Educational Supplement "Sir is a knight... but Miss is ridiculous - it doesn't match Sir at all".
She said she had been struck by the disparity while volunteering in a secondary school.
But one educationalist said being called "Miss" was a sign of respect.
Prof Coates, emeritus professor of English language and linguistics at the University of Roehampton, said she had been surprised by the different titles given to male and female teachers.
"I didn't think there was this awful disparity between professorial status and these young teachers, but they're all Sir and I'm not.
"It's a depressing example of how women are given low status and men, no matter how young or new in the job they are, are given high status."
Professor Sara Mills of Sheffield Hallam University said UK schools were moving towards allowing pupils to address their teachers by their first name.
"Sometimes teachers find that they can control students more when they try to stress the similarities between them, rather than trying to keep as distant as possible," she told the TES.
But Debbie Coslett, chief executive of the Brook Learning Trust in south-east England, said there was not a disparity between "Sir" and "Miss".
"My response is always that my name isn't Miss; it's Mrs Coslett.
"But if I'm in a school where students don't know me and they call me Miss, I'm fine with that. They're showing respect by giving me a title."