Almost a decade ago, a strict set of rules was introduced to ease the burden on overworked teachers. However, new evidence suggests that one of the results has been to "exploit" support staff, who are forced to teach pupils despite not having the necessary qualifications.
A survey by the ATL education union of its members in Wales claims to have uncovered widespread misuse of staff working as cover supervisors. They are only supposed to oversee lessons, but nearly two-thirds of schools are using supervisors to teach and a third of schools are using them to prepare and mark work, according to the union. Both contravene the rules governing their jobs.
The findings, which have emerged from a survey of 200 teachers and support staff, have prompted concerns that the issue could extend to the use of cover supervisors in England.
Since 2009, schools have been bound by rules that mean they can only ask teachers to "rarely cover" for their colleagues' lessons. It was one of the final acts of the workforce agreement of 2003, which also removed a host of administrative duties from teachers and paved the way for the rapid expansion in the number of teaching assistants.
The use of cover supervisors has proved contentious for some time, with concerns being raised that staff require no formal qualifications. Claims were made by the NUT in 2009 that nightclub bouncers had been employed in the role.
The ATL survey indicates the extent to which cover supervisors are being used to take on routine teaching duties, despite the "rarely cover" policy having been in place for more than two years. More than 20 per cent of respondents to the survey said that cover staff were being used to plug gaps when teachers were on long-term sickness absence, and almost 40 per cent reported that support staff were covering for teachers' planning, preparation and assessment time.
Wales's performance in the 2009 Pisa (Programme for International Student Assessment) tests, described by critics as "disastrous", prompted a drive to improve standards in all schools. However, Philip Dixon, director of ATL Cymru, said the survey showed that staff were being used in roles for which they had no proper training.
"It means that some children in some schools are not always being taught by a properly qualified teacher," he said. "The figures also show that support staff are being routinely exploited, and are being expected to deliver services for which they are not being paid or rewarded."
Dr Dixon called on the Welsh government to insist that local authorities uphold the workforce agreement and make sure staff are not exploited. Unions say that the agreement was never monitored as closely in Wales as it was in England, which is partly why the current situation has developed.
It is claimed that since the scrapping of the social partnership - which used to bring unions and politicians together - by the Westminster government, contravention of the rules is also a growing problem in England. Paul Maloney, senior officer for school support staff with the GMB union, said that abuse of support staff was a "common picture" in schools.
"Every day when we go into schools, support staff tell us they are being used and abused in these ways," he said. "Unqualified staff are being used as cheap labour and it is becoming more commonplace."
In 2009, Unison carried out a similar survey and found that 68 per cent of its support staff members were regularly covering for absent teachers. Around 10 per cent claimed they were covering up to 15 lessons a week.
Christine Lewis, Unison's national officer for education, said: "We have no indication that these practices have lessened and, as financial pressures bear on schools and academies are given more freedoms, we expect them to become even more common."
In the ATL survey, one respondent claimed: "In the last month, I know of at least two instances where a cover supervisor has been used to cover a member of staff for a period of one week in one instance and three weeks in another until challenged by our representative."
Administrative staff are also being used to teach, it is claimed. "I devise, produce and mark library lessons for Year 7 pupils, as well as mentor several pupils and babysit all-year groups who use the library and adjacent room during the school day," one such staff member said.
The Welsh government said that responsibility for the appropriate deployment of staff rests with heads and governing bodies. "The agreement is unequivocal that teaching assistants and teachers are not interchangeable and that support staff should work under the direction of qualified teachers."