Unqualified school helpers are being used as cheap labour to teach A-level and GCSE classes in subjects about which they know nothing when specialist subject teachers are on leave, a union claims.

In the very worst cases, an untrained assistant was required to teach A-level English for an entire term, while another was put in charge of a GCSE maths group.

Other instances include former dinner ladies and prison officers replacing qualified supply teachers.

The practice was condemned as an “absolute scandal” yesterday by members of the National Association of Schoolmasters Union of Women Teachers (NASUWT), who likened it to putting an enthusiastic member of the ground staff in charge of flying a plane because the pilot and co-pilot had not turned up.

The likely result was a reduction in quality of education, a decline in classroom discipline and a danger that work will dry up for fully qualified supply teachers, the union’s annual conference in Belfast heard.

Government reforms to teachers’ working conditions in 2003, supported by the NASUWT, brought about a reduction in teachers’ hours and specified that teachers would not have to cover each others’ classes for longer than 38 hours a year — or an hour a week.

Instead, classroom assistants and cover supervisors, who are not teachers and who are paid about £13,000 a year, would be given a far greater role.

But Peter Wathan, a delegate from Bedfordshire, told the conference that unscrupulous head teachers were exploiting them as “cheap labour” by assigning them their own lessons.

He cited the case of a popular school in his area that was using an unqualified cover supervisor to teach a GCSE maths group.

“It happens to be a lower stream group — perhaps they don’t deserve a qualified teacher in the head’s opinion,” he said.

Austin Murphy, a supply teacher from Leeds, said that the scale of the problem was far greater than people realised.

“I do know of a school in south Leeds where a cover supervisor was asked to take on this role for maternity leave,” he said. “They did GCSE and A-level classes. This person has no experience whatsoever in that subject.

“Clearly this is an absolute scandal. It should be known that this is happening,” he said.

Pat Lerew, the union’s former president, who is now a supply teacher, said that putting cover supervisors or teaching assistants in charge of children while they complete worksheets prepared by an absent teacher could lead to a breakdown in discipline.

“Pupils churning out reams of work with no feedback will rightly lose motivation and ask what is the point of this,” she said.

John McCarthy, a fully qualified supply teacher from the union’s Cannock and mid-Staffordshire branch, said that he was being deprived of work because lessons are covered by assistants, including, at one school, a former dinner lady and a former prison officer.

Delegates backed a motion that replacing qualified teachers with cover supervisors will “lower the quality of children’s education”.

A spokesman for the Department for Education and Skills said that official guidance made it absolutely clear that cover supervisors do not teach.

“We have record numbers of teachers in our schools with over 35,000 more than in 1997. We have also removed many administrative tasks from teachers and overseen a doubling in the number of support staff to help free up teachers’ time to do what they do best — teach,” he said.

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