"Ninety-three per cent of all communication is non-verbal and only 7 per cent is in the words you actually say!"
Amazing, isn't it? Yes, and it's also rubbish. If it were true, we wouldn't understand the radio and we wouldn't need to learn Spanish. Clearly, however, tone of voice and body language are important. Excellent work is now being done to help children who have not learnt these crucial non-verbal skills and are therefore driving their teachers nuts. To appreciate this work, though, we must go back to the origin of that daft 93 per cent statistic.
In the late 1960s, ground-breaking research into communication and body language by Professor Albert Mehrabian found that in some situations, 7 per cent of the attitude was conveyed by the words, 38 per cent by the voice and 55 per cent by the face. People added 38 to 55, got 93 and applied it to all spoken communication. This is where that daft "93 per cent of everything we say" comes from.
Mehrabian's findings - and his book, Silent Messages - are relevant to teachers.
"You need these skills to make and keep friends," says Sioban Boyce, a communication and behaviour specialist. She helps children who have not learnt to interpret non-verbal cues such as facial expressions.
"Peer communication is a nightmare of complexity," she says. It's true, and builds on Mehrabian's findings; friendships develop with shared feelings and attitudes, subtly conveyed. In her book, Not Just Talking, Boyce describes the child who "doesn't recognise when his teacher first begins to feel annoyed by his behaviour and only takes notice when she has got to the point of being absolutely furious."
We have all met those. There is hope, however. Boyce showed us before-and-after video clips of a six-year-old boy whom she had helped. The difference was extraordinary. At first, he did not make eye contact and could not tell that a grinning man in a photograph was happy.
After 19 half-hour sessions with Boyce, he was looking at her, laughing and explaining why he found a photograph of a boy with ice-cream on his face so funny. The change was so great that he will probably not now be diagnosed with Asperger's syndrome. There are limits to what some autistic children will learn but they can still benefit, says Boyce.
"Babies and children need to watch hundreds of faces in conversation to understand and use facial expressions themselves. This happens less today, with online shopping, fewer meals around the table and buggies that face away from the parent."
So next time you sense the whole class watching you and a colleague share a joke, you will know why they are so fascinated by your faces. On these grounds alone we could justify spending an entire lesson just chatting in front of our pupils. It would do them a power of good.
Catherine Paver is a part-time English teacher and writer. Find more information about Sioban Boyce at www.notjusttalking.co.uk.