A drive to give pupils unlimited choice over what and when they study is “impossible to deliver”, a teachers’ leader has warned.

Kevin Campbell, president of the Scottish Secondary Teachers’ Association (SSTA), said schools could not meet the demands the curriculum placed on them.

The warning comes after the introduction of Curriculum for Excellence (CfE) which aims to offer greater flexibility to pupils.

However, academics have warned some subjects have been squeezed out as a result of teacher shortages and timetabling clashes in fourth year.

Mr Campbell, who will address the SSTA annual congress on the issue today, said: “The desire to offer pupils everything, when they want it and how they want it just can’t work.

“There just isn’t the resources. There aren’t enough teachers or rooms. There also isn’t the expertise amongst senior managers to be able to design the parameters within which all this can be delivered.

“This inevitably leads to the situation where a teacher has to contend with multi-course classes, split classes, sharing rooms, a lack of resources, over-subscribed classes and reduced teaching commitments.”

Mr Campbell said teachers were being forced to do an “impossible job” with pupils ultimately suffering.

And he went on to criticise the way CfE had been introduced as an “absolute nightmare” for the teaching profession.

He said: “It has been, from the start, a half-baked hodgepodge of semi-rational notions of pedagogical rationales and curricular inconsistencies.

“At virtually no point in its history has our profession been fully consulted in its ideological underpinnings, curricular necessities or implementation.

“Indeed, at every turn the voice of teachers has been ignored. We continue to spend unthinkable volumes of time and effort in trying to make this system work.

“We need to say enough is enough. Our health, our families and our sanity should be worth more than sorting out the mess that our education system is in.”