Support staff 'plugging more teaching gaps'
School support staff are being asked increasingly to teach lessons to cover the gaps caused by staff shortages, a poll suggests.
Some (78%) of those surveyed by the Association of Teachers and Lecturers say the work they do when covering a class is the same as that of a teacher.
The union said schools did not have enough funds to replace staff when they leave because of tightening budgets.
The government said schools should not use support staff to replace teachers.
Support staff who act as cover supervisors are only supposed to supervise the pupils not to teach them.
The ATL survey of nearly 1,000 members working as support staff suggested there had been a rise in such staff covering lessons in a more formal way.
'High quality lessons'
A similar survey by the union the previous year suggested less than two-thirds were teaching lessons.
And just over seven in 10 (72.5%) of those who responded to the question said it had not been possible to supervise a class without effectively delivering a lesson.
One primary school teaching assistant in Buckinghamshire told the union: "We are expected to deliver high-quality lessons not just supervise the class."
And a higher-level teaching assistant (HTLA) working in a secondary school in Durham said: "We are told sometimes with only five minutes or less notice that we are covering lessons.
"We are expected to teach students."
ATL general secretary Dr Mary Bousted, said: "As these results show, support staff are feeling the pressure to actually teach lessons and to plug the gap in staff shortages when teachers leave and do not get replaced.
"As the government continues to squeeze school budgets, there simply aren't enough funds to replace staff.
"It is worrying that this year more support staff feel the work they do when acting as cover supervisor is identical to that done by supply teachers, with an increase of 14%."
Rob Webster, who has overseen a project on maximising the impact of teaching assistants at the Institute of Education, said: "The survey results suggest TAs, cover supervisors and other support staff are being deployed to backfill teaching staff shortages on top of covering their existing demands, all at the same time as overall staffing numbers are in decline."
The warning comes amid continuing concerns about a growing teacher shortage in England, especially in disadvantaged schools and subjects such as physics.
A major report published last year found that UK schools are more hindered by staff shortages than many of their international counterparts.
The Programme for International Student Assessment (Pisa) study, which covers 72 countries and economies, found a "relatively large share" of UK head teachers reported that their school was affected by staff shortages.
A Department for Education spokesman said that while teaching assistants were allowed to teach classes "we are absolutely clear that schools should use them to add value to what teachers do, not replace them.
"It is up to individual schools to decide how to train, develop and use their teaching assistants effectively."
The spokesman added that the core schools budget had been protected in real terms with so that "in 2016-17 schools have more funding than ever before".