GCSE pupils think that looked ends with a t, coming should be spelled with an e, and that it is possible to suffercate from angshuseness.
Researchers for Cambridge Assessment, which owns the OCR exam board, studied the spelling mistakes found in 60 GCSE English exam scripts. They found that while 97 per cent of words were spelled correctly, many GCSE candidates were unable to spell basic words. These include words that children are expected to master by the age of seven, such as looked, there and was.
These candidates are likely to have the support of John Wells, emeritus professor at University College, London, who this week called for the liberation of the English spelling system. He claimed that spelling should reflect contemporary priorities, such as text messaging and emailing.
But there were relatively few text message spellings in the GCSE papers studied by the Cambridge academics. Instead, the most common mistakes involved uncertainty around double letters.
So pupils were unsure whether they should always sit quietly until the teacher stopped harassing them or allways sit quiettly untill the teacher stoped harrassing them.
It was common for pupils to confuse two similar sounding words, like know and no or their and there.
And there were those who understood that w was occasionally followed by h, but took to the principle slightly too enthusiastically: I whant, he whas and we where.
Teenagers also showed themselves unfamiliar with other basic rules of primary school spelling. This led to spellings such as unnaturely or comeing, as well as less logical variants, such as slightley, angrey and inevitabely.
Other errors tended to reflect pupils' speech patterns. Many ending words with -ink instead of -ing: somethink or nothink.
The most errors involved multiple misspellings. These included constructions such as impaitientley or nieghbor, which the researchers described as "all the right letters, just not necessarily in the right order".
And there were words so badly misspelled as to be barely recognisable: gourges (gorgeous), angshuse (anxious) and formiler (familiar).
Where words were even more extremely mangled - nufse (nervous), faunt (thought) or torck (talk) - the Cambridge researchers suggested they may be caused by dyslexia.
Ian McNeilly, of the National Association for the Teaching of English, points out that it is possible to achieve high grades in an exam with poor spelling. Many teachers therefore overlook spelling in favour of grade- inflating skills.
"I'm not saying that we make spelling a huge priority over understanding, analysis and interpretation," he said. "But students should be able to spell securely. It's an ongoing battle, that isn't helped by wider society."
But Professor Wells believes that wider society has its priorities right. "People should be able to use whichever spelling they prefer," he told the Spelling Society's centenary dinner on Wednesday.
"We should no longer fetishise the ability to sort out their, there and they're. There are more important things in life."