I know some people who in effect consider that term more or less synonymous with 'unblemished praise'-where criticism means appraisal and constructive relates chiefly to the building of ego! And in truth there are some occasions when that is the essay-marker's task-and very nice they are too, for student and teacher alike. But the term has another, more muscular application: it consists of telling the student where s/he has gone wrong or somewhat awry. Such criticism is never easy to take, but if absorbed humbly, it allows you to construct something better in the future. It is part of the building process that lies at the heart of any good teacher-learner partnership.

The key point here is that you cannot construct something out of nothing. One can do a good deal to help improve material logged on a page that has some flaws; one can do very little about material that needs to be there and is wholly absent, apart from point that fact out and advise the student to fill the gap. That isn't constructive in any but the most rudimentary, informative way; but-as I've occasionally had to remind students of mine-nobody can be very constructive when faced with a void.

So it is far easier for a teacher to help students if they've written too much, or if some of what they've done is off-key or unconvincing, than if they've written too little or missed out important matters. In the former instance, one enjoys in effect a detailed and positive 'dialogue' with the student, who is able to make immediate and productive strides forward. In the latter instance, no such dialogue is possible: only two recourses are available to the teacher. The soft option is to identify what is missing and more or less leave it at that; the snag is that:

One does not know whether the student understands why it's important or whether s/he will cover the necessary additions afterwards. The tougher route is to say simply, 'Do it again'. Such a suggestion is always depressing and often very annoying, but it is inescapably sound, if only because

It is always easier-whether immediately or at some time in the future-to edit work that is too long, partially unsuccessful or at times flabby than it is to flesh out work that is too thin. Almost invariably, the latter exercise evolves into a complete re-write, starting from scratch.

In short: the exploratory essay allows you to use your teacher in a rich and constructive way; to settle for a bare minimum in such tasks is always an unwise waste.