The fall in Scottish exam pass rates reported by The Herald yesterday is the latest in a series of dismaying stories about Scottish education.

But on none of these has the Government offered a satisfactory explanation or an acceptable solution.

First, though, is there truly a problem? Is Education Secretary John Swinney not correct to say pass rates fluctuate from year to year?

Perhaps, but the trends don’t actually fit that kind of pattern because they are too relentlessly downwards.

Fluctuations would most probably be due to students switching between subjects.

If the pass rate goes down in, say, history, then that subject might temporarily acquire the reputation of being difficult.

So some weaker students might switch to modern studies.

Then its pass rate would fall, and history’s would rise again, and the cycle would go back in the other direction.

But that’s not what has been happening.

At Higher, pass rates have been falling or at best stable in the last few years in all the big social subjects, in the main sciences, and in the most popular languages.

The pass rates have rarely risen. A dropping pass rate is not followed by a rise, which is what would have to happen if Mr Swinney’s fluctuation theory were the explanation.

So we have to delve deeper into the report, where we find some more plausible clues.

One is in the repeated comment that students lack knowledge.

In all the sciences, the report says students were “unable to demonstrate accurate knowledge and understanding of definitions and terminology”.

That’s damning. Science is nothing if it is not about accuracy. In maths, students at all levels had “weak numeracy”.

That means they couldn’t count. At Higher, they were poor at algebra. Not being able to manipulate either numbers or symbols doesn’t leave much else in maths.

In English, candidates mistook opinions for facts. In geography, they made sweeping or stereotypical generalisations.

In history they tended to regurgitate model answers that had been learnt by heart.

None of this suggests a particularly stimulating curriculum.

In short, Scottish students are not being grounded in the basics of knowledge and understanding, or in the skills that come only with a rigorous attention to these.

And that brings us yet again to the elephant in the room, Scotland’s “curriculum for excellence”.

Most of the deficiencies the examiners have reported in the exams should have been dealt with many years earlier in these young people’s lives. You should learn to count in early primary.

You should learn about accurate observation when you start doing proper science in late primary or early secondary.

You should understand the difference between an opinion and a fact when you grow out of childhood.

The best psychological research on how children learn shows the only way to teach these skills is by embedding them in a rich context of knowledge.

Yet Curriculum For Excellence does not do that. It speciously supposes that you can learn skills de-contextualised.

But no-one can think without having something to think about. The Government’s report this week is all too ready to blame teachers for not understanding recent changes.

It says tat the exams need to be better “aligned” with the curriculum. It says schools need to concentrate on teaching and learning, as if any school ever thought otherwise.

But it never seems to have crossed the minds of the report’s authors that what may be at fault is the curriculum itself.

Lindsay Paterson is Professor of Education Policy, Edinburgh University.