[John Bennett]

I think the issue is that coursebook writers choose to ignore the distinction on the basis that it will be 'simpler' for their audience - students and teachers alike. I don't feel there is a major problem with the difference itself. I disagree with the view that not explaining aspects makes learning English easier. Having said that, I do accept that the explanation is best left until intermediate level. However, I wish that coursebook writers would be more careful with their use of the word 'tense'. I have found that a clear explanation reinforced with examples can actually clear up some of the things that confuse students. It is also very helpful to be able to show my Russian students that all perfect 'tenses' have something in common. This is especially so because Russian has no equivalent to perfect. A short and simple definition of progressive/perfect can be found in the Longman Dictionary of Language Teaching & Applied linguistics.