I can spot a child with Down syndrome at 100 metres with their backs to me. I don’t think it’s anything to do with having spent 25 years in special education; human beings seem to be programmed to detect differences in others. In the case of the back view of a person with Down syndrome, it’s a slight shortness of stature and flatness of head. But you don’t need a learning disability to get picked out as being different. Just being a little bit shorter or taller than average, a little bit fatter or thinner, having slightly protruding teeth or sticky-out ears, redder than average hair, eyes that don’t quite line up, more hair than normal, a gait that isn’t quite even, a voice of a higher than usual pitch - all these things are quickly spotted.

Think of the teasing at school. You don’t have to be that different to get called Porky, Spotty, Four-eyes or Carrot-top or, unluckily for some, all four. Outstanding beauty also gets noticed; this seems to be about being “super average”. Look at the way celebrities such as David Beckham, with his symmetrical features, or Elle McPherson, with her perfect figure, are celebrated and fawned upon by the media; but get a little too thin, like Calista Flockhart, or too fat, like Vanessa Feltz, and the criticism begins. Even our most intelligent and right-on comedians know they only have to refer to Ann Widdecombe or Robin Cook in terms of their looks to get audiences rolling around laughing. Why?

There must be some basic reason, some fear of difference or need for safety in homogeneous groups that humans instinctively seek; maybe it’s relief that it’s not them being laughed at. If you’re taller and thinner than normal, as I am, you’ll know how people feel entitled to ask: “How’s the weather up there?” How rude! And it’s not a big step from name-calling and teasing to full-on bullying, as the Friday behaviour series has been so graphically demonstrating.

In contrast, special schools have a very accepting environment. The children often look, sound and move in unusual ways, but we relate to them as individuals and try to make sure no one feels left out or different. But even in a special school, where acceptance, inclusion and embracing and valuing difference are key, we can still fall prey to being influenced by looks. Emma came to school today in yet another new, pretty dress. She can do little but smile, but what a dazzling smile she has. I watched as she was pushed up the corridor in her wheelchair. “Good morning, lovely girl,” called Charlie. “Hello Emma, aren’t you a pretty girl today,” said Chris.

“Hi, Ems. You look lush.” “Hi Emma, what a lovely dress - and hair decoration to match.What a bobby dazzler.” Fair enough. Emma’s new dress gave us something to comment on and share; something positive to interact with her about. Her parents seemed to know that pretty clothes and accessories would give Emma all these positive encounters during the day.

Next came Lottie, a child the same age as Emma, also a wheelchair user but whose mum always dresses her in a navy blue track suit. Nothing wrong with that, of course, but nothing to comment on either. Lottie is tube-fed and has a nasogastric tube, and she dribbles a lot. She has Mobius syndrome, which means she can’t smile, but those who work with her know when she’s happy. The staff care about Lottie as much as they do about Emma and I know she gets just as much attention in class. But listen as she is pushed up the corridor. Nothing.

Maria Corby is deputy head of a special school for pupils with severe and multiple learning difficulties. She writes under a pseudonym