Once one of the best in the world, Scotland’s education system has been steadily marching backwards for the past ten years. From the outside, it seems baffling: why, given that Scottish spending per pupil is among the highest in the world, are things going so wrong? From the inside, it’s far easier to understand. You can explain it in three words: Curriculum for Excellence.

I’d heard stories about it before I started training as a teacher. By the time I qualified — in April last year — how I wished I’d listened to them. The story starts in 2010, when the new system was introduced with four aims: to create ‘confident individuals’, ‘successful learners’, ‘responsible citizens’ and ‘effective contributors’. Perhaps the meaning of these phrases was clear to those who came up with them. But as I found out, many teachers can’t recall — let alone explain — them.

Picture a grey Glasgow sky and underneath, a cosy school staffroom. ‘What are they called again? Successful contributors? Effective learners?’ one teacher with 30 years’ experience asks. ‘No, no. It is the learners who are successful; the contributors are effective!’ a student teacher replies helpfully.

The idea of teaching had been turned on its head. Rather than stick to a topic — like English or chemistry — we had to mix them up according to a bizarre formula created in the devolved parliament. In 1999, the new MSPs had been given power over the school system — so decided to use it. When the SNP came to power, the shake-up began. Devolution made a nation’s children into guinea pigs.

So instead of straightforward maths lessons, we’d have ‘interdisciplinary learning’. Bar charts would be shoehorned into lessons about Shakespeare. For a teacher to perform ‘active learning’, the ‘learners’ had to be constantly entertained. Then came the demand for ‘collaborative learning’, which means group work, where nothing gets done.

Exams were to be judged by classwork, which of course created plenty of scope for foul play. And not only by pupils. One experienced teacher told me of ‘the pass factory’ in her school, a place where pupils go for unlimited attempts on core assessments. Gaming the system is particularly noticeable in middle-class areas, where children pay for private tutors in order to be coached through exams. In some cases, tutors actually write the coursework for them.

In English, graphic novels crept their way into classrooms. Literature and media studies were fused. Presumably to cater for this, Penguin even published an emoji series of Shakespeare’s plays. This is new, certainly, but is it progress? Glaring ignorance of world geography or history is not just permissible, but expected. In history, for example, it’s normal for pupils to study the second world war year after year, and merely be assessed at different levels, constant assessment being the SNP’s only guarantee. The number of pupils studying French or German has halved.

All of this was supposed to empower teachers and give them more say. But the SNP failed to do its homework, and it didn’t quite turn out like that. And so, despite teachers’ sceptical willingness, the whole project has become seen as a sick joke. In the staffroom, the Curriculum for Excellence is known as the ‘curriculum for excrement’.

My final teaching exam led me to cater my lesson to the 20 pupils in front of me, of whom 18 had various ‘additional support’ needs (autism, dyslexia etc). Trying to fulfil the curriculum’s bizarre demands on top of these challenges made my lesson a circus. In the end, I qualified. But I walked away from teacher training with a smoking habit and a resolution never to return. I later found out that four in ten newly qualified teachers leave the profession within a year. Which is a tragedy: all of my fellow trainees entered wanting to help pupils, as we had been helped. But it’s hard, once you find out that you’ll be taking part in the dumbing-down of a nation’s schools and the betrayal of its children.

I know quite a few of the dropouts now. There’s the Frenchman with a degree in philosophy from the Sorbonne, who stormed out of our school placement after a disagreement about the quality of his teaching. A fellow secondary school teacher who, due to unmanageable stress, now tutors young offenders rather than return to the classroom. A once enthusiastic primary teacher who said to me, ‘I’d rather do anything — anything — than go back.’ At the last count, there were almost 700 vacant teaching posts in Scotland. That’s around 21,000 pupils who are missing teachers.

In the staffroom of one school where I taught, there was a poster. It read, ‘Being a teacher is easy. It’s like riding a bike. Except the bike is on fire. You’re on fire. Everything is on fire. And you’re in hell.’ Sometimes, on breaks between classes, I would sit and stare at it. I did not see the funny side; for the teachers, or for the pupils, who are the principal victims of a system that is so visibly failing.