On 16 May, 17:38, Alastair wrote:

Perhaps I am teaching my granny to suck eggs because I thought all
teachers were now aware that their pupils go to Wikipedia and use that
text in their assignments.

Anyway, I dislike students posting questions on newsgroups in order to
get the answer to their homework. *So promise not to use any of this
in your lessons :-)

Thank you for your contributions gentlemen, especially Alistair who
seems to think me incapable of searcing wiki and the havens of the
average student who like to copy and paste their essays into a word
documanet:-)

I asked here in the hope of any knowledge of academic research that
may be factual rather than pure fantasy - all the usual easily
accessible links have been well covered, thanks.

Thanks Martin too - you never let anyone down on this ng:-)

Steve J