The truth is that this notion has been dreamt up by curricular enthusiasts without, it seems, very much idea of what motivates children to learn. And motivation is surely what matters if schools are going to compete in the age of the Internet, which brings excitement to the way youngsters find things out for themselves - even if this is no more, initially, than downloading the latest craze.
Very often that involves endless "depth" of study or play, and breadth and balance go out of the window. But that is the reality of how youngsters approach their learning - capturing their interest might be another way of putting it.
Michael O'Neill, the North Lanarkshire director, may have come close to admitting this in his comment about pupils being allowed to pursue their talents and interests, see them flower and get a sense of purpose out of achieving something. Now that would be revolutionary!
Peter Richardson Perth Road, Dundee