This thread has taken an interesting turn. Rabanito asks; "You mean, you can teach any student? Or are there students for whom you can not do anything?", and Peter replies; "Before I go down this road with you I need to know your real name...Just so I can do a google search on you, to understand better with whom I'm conversing."
I think Peter's response would have been more appropriate if Rabanito's question had been, "You mean, you can teach me?", but that wasn't his question.
I think it's obvious that a teacher in any subject will not be equally effective in teaching all individuals, considering the great variability in human characteristics, intelligence, cultural background, personal experiences, and so on.
An extreme example is the situation of the Aboriginals in Australia. I get the impression that a major cause of the inadequacy of the teaching in Aboriginal schools, especially in remote communities, is due to the 'white' teachers' lack of understanding of Aboriginal culture and language. The teachers are therefore unable to engage and communicate with the community, build up trust with the kids, and serve as role models.
As regards the issue of some people, like me, not revealing their personal details on internet forums, I tend to agree with Amolitor. Why take the risk if it's not necessary. There are so many 'ad hominem' attacks on internet forums, one cannot be sure whether some of them might lead to an undesirable outcome if one's full name and location is revealed.
One's real name and current residential location need not have any bearing on the validity of any argument one is presenting on an issue.