Once upon a time, the Scottish education system was the envy of the world but its reputation came crashing down when the Programme for International Student Assessment (Pisa) ratings were published late last year.

They showed that in 2018 Scotland’s attainment in maths and science had taken another dive - following on from the falls also seen in 2015 and 2012.

This should be a wake-up call to everyone in the UK education system who advocates progressive education.

Analysis: What does Pisa tell us about Scottish education?

Quick read: Scottish curriculum review to be led by OECD

‘Slipping down’: PM attacks Scottish education

A teacher’s view: What I found when I moved from England to Scotland

Background: What is Curriculum for Excellence?

Progressive education has been steering Scottish schooling since the curriculum was phased in from 2010.

“Vague,” “lacking in clarity”, “wishy-washy” - just a few phrases that perfectly sum up Scotland’s very poorly named Curriculum for Excellence.

A closer look at the curriculum in maths, in particular, shows it to be highly experimental in its approach.

And overall the Curriculum for Excellence focuses on the exploration of topics rather than the solid teaching of technique in a more traditional format.

This is a move away from the more traditional approaches that characterised Scottish education and produced such great minds as Adam Smith, Andrew Neil, Michael Gove, Gordon Brown, Duncan Bannatyne - to name but a few renowned people from across the world of politics, business and the media.

Why Curriculum for Excellence is failing

What the Scottish system now offers is the same progressive approach that was tried - and failed - in England in the 1960s. This approach highly influenced the curriculum reforms that were included in the Education Reform Act of 1988, which gave rise to the then national curriculum. Subsequent reworkings of this legislation in the 1990s gave us the lamentable National Numeracy and Literacy Strategies, which further embedded progressive approaches into law.

Thankfully, the powers-that-be in England recognised in the 2010s that the progressive approach of the 1960s, which was actually reinforced by a national curriculum in the late 1980s and early 1990s, had let down generations of children (and left us floundering in the Pisa rankings).

This led to an overhaul of the national curriculum in 2014 that finally started to address these issues. This new curriculum has been particularly successful at primary level, where a return to more traditional and structured teaching methods has led to improved performance. I was proud to be an adviser to the UK government on the 2014 maths curriculum, which led to many of these changes.

And those changes are starting to embed and the children that have been through primary education under the new curriculum are producing better results at secondary level than their predecessors.

The evidence of those improvements was seen in the most recent Pisa rankings in which England rose up the table.

Pisa - a study of the test scores of 15-year-olds across 79 countries - shows that students in England performed significantly better in maths in 2018 than 2015, and also outperformed the Organisation for Economic Cooperation and Development average in reading and science.

Its score in maths was much higher than the other countries of the UK, including Scotland.

There were no statistically significant differences between scores for reading in England and Scotland but in science the score in England was significantly higher than Scotland.

The key to success in education is getting it right at primary level. It is at this stage in a child’s education that they need to be able to grasp the basics.

Structured and methodical teaching helps to ensure that children are equipped with the key basic skills in numeracy and literacy before they go into the secondary system.

If they have not grasped the basics by the time they go to secondary school, it is so much harder to correct. Children who are not sufficiently numerate will fail in maths, science, design and technology and any technical subjects. If they are not very literate, they will struggle in English and all the humanities.

Scotland is a great country and I hope for its people that the politicians wake up sooner rather than later about the crisis facing it.

And it is a crisis.

The education of young people is the key to unlocking the future potential of a country and its economy. Get it right and everything else will fall in place - getting it wrong can only lead to stagnation and failure.

Dr Stephen Curran is an education writer and former adviser to the UK government, who previously worked as an English and drama teacher. This article originally appeared on his blog.