When A-level grades are published on Thursday, we can expect two familiar analyses of how the school-leavers of England and Wales have performed.

According to one, our children are working harder and displaying greater intelligence than children of previous generations, explaining why around one in five grades given is an A. Twenty years ago, it was more like one in 10. The other theory will be that exams are getting easier, that marking is more lenient and that things ain't what they used to be. Parents who watch their kids sweat over revision tend towards the brighter view. University tutors, who struggle to distinguish excellence from mediocrity among a sea of straight-As, tend to be more pessimistic.

As we report today, the independent exams regulator has come down on the side of the optimists. Ken Boston, chief executive of the Qualifications and Curriculum Authority, says critics of the modern A-level are elitists pointlessly hankering after a bygone era when only a privileged few went to university. Today, 43 per cent do. The government's target is 50 per cent by 2010.

The A-level is a victim of its own success. Teachers have become better at coaching pupils to get good results. Pupils are better at feeding in the right answers. The system is delivering just what is expected of it - higher grades.

We should stop worrying about whether exams are easier. The issue is, rather, what we want exams to do for children and how that differs from what we want schools to do for them. Universities and employers need exam results to indicate ability. If everyone continues to improve, they will inevitably look for ways of measuring greater achievement - the International Baccalaureate, for example, or simply ask the exam boards to recalibrate A-level grades.

But schools are not all about testing. Alan Bennett's play The History Boys, now made into an excellent film, brilliantly depicts the difference between teaching for exams and teaching for love of learning. It celebrates erudition as an aspiration that can and should ignore class boundaries. Too often today, it does not. Learning for its own sake has foolishly become identified with snobbery and elitism. The problem is that giving teachers the freedom to inspire will mean loosening the structures that bind them to achieving exam targets. And jeopardising those annually improving grades.

When this year's school-leavers celebrate the rewards of their hard work on Thursday, we should congratulate them. They and their teachers have done exactly what has been asked of them