Just because someone has identified that there is an hierarchical structure to some body of knowledge doesn't necessarily mean that the human species has to learn that hierarchical sequence in some kind of rigid linear progression. That's not how we have been 'wired' to make sense of and ultimately apply all the complex things we have to learn.

As John Holt once quipped,"If we taught kids to walk and talk that way we'd raise a nation of mute cripples".

Sequential may be a better word than hierarchical but whether it is a concept in mathematics or whether it's a three-part TV drama you won't know what's going on if you enter at a point which has antecedents you don't know about. A vague idea and a comfortable feeling maybe, but not understanding.

I think individual learning through well-balanced and constructed internet programmes is certainly the way to go. Poor teachers, of which there are many, obstruct learning just as effectively as recalcitrant pupils. While an educator must have a certain level of education and competence, this must not be confused with the ability to teach and pass on the information, ideas and values inherent in a discipline. I am sure internet schooling could be devised to suit all disciplines, with webcam discussions between teachers and pupils from time to time. My problem is with the content; values and unquestioned assumptions. I would be horrified if my child unconsciously imbibed the world outlook of right-wing or religiously orientated tutors, or if they were fed, albeit unconsciously, notions of expanding economies, short term profits, human superiority and so on. Internet learning would also eliminate classroom bullying by both teacher and peers, making the learning experience happier for the majority of students, and might even stave off the class and religious wars that are going to be the ultimate result of Australia's current system of elitist religious schooling.

Kahn is brilliant and I love his website. I wish it had been available, when I was a kid.