Thanks for the link to the useful article. It went on to say that:-

"One of the greatest injustices is that Americas best teachers overwhelmingly teach Americas most privileged students. In contrast, the most disadvantaged students invariably get the least effective teachers, year after year until they drop out." I almost caused a mutiny in one Chinese university when I suggested that we stream students according to their ability and then gear the teaching to that level using different materials. After some heated debate, the Professsor in charge agreed and we split the groups. All the students made better progress but with the caveat that staying in a particular group was dependent on maintaining that level in their performance.

From personal experience I have seen some woefully inadequate native English teachers in China but there did have something in common. They were all young graduates with no teaching experience at all or TEFL type qualifications and came from the USA, I'm sorry to say. What the research did not appear to consider is what 'Americas best teachers' have that the others don't have, and if there is a correlation here between academic achievement or sound classroom practice or management and student success.

When a speech on education from 'Dubya' (George W. Bush) contained the line, " Is our children learning" perhaps we can understand a little of the problem. Part of his education was at Yale and Harvard!