Pupils receiving help 'do worse'
There are more than 180,000 teaching assistants in England's schools
Pupils who receive help from teaching assistants make less progress than classmates of similar ability, a government-funded study suggests.
The Institute of Education assessed the impact of the huge expansion in support staff in England and Wales since 2005 by studying 153 schools.
It said such staff tended to look after the pupils most in need, reducing their contact with the qualified teacher.
The government said teacher workloads and class behaviour had improved.
The expansion of the school support workforce, which began in 2003, was also intended to raise quality, giving extra support to children with special educational needs.
The more time pupils had with support staff the less time they had with the teacher
Professor Peter Blatchford
The Deployment and Impact of Support Staff (DISS) project surveyed 20,000 teachers and analysed the help received by more than 8,000 pupils in 153 schools in 2005-6.
The researchers were so surprised by the results of their study, that they repeated it for 2007-8 and came to the same conclusion.
Lead researcher Professor Peter Blatchford said the results could not be explained by the lower attainment, special educational needs, family backgrounds and behavioural problems of those pupils who had help from teaching assistants as those factors had been accounted for.
He added: "This is not something that we should blame on teaching assistants - we are not saying they are a bad influence.
"It seems to be about the way in which they are deployed and the way in which they are managed.
"The main explanation seems to be that support staff tend to look after the children in most need. They can then become rather separate from the main curriculum.
"The more time pupils had with support staff, the less time they had with the teacher."
Support staff tend to have less training and a lower level of education than teachers.
About two-thirds of the support staff in this study had not been educated beyond GCSE level.
A spokesman for the Department for Children, Schools and Families, which funded the study along with the Welsh Assembly, said support staff were the backbone of the teaching workforce.
"There is clear evidence that there is a positive effect on pupil's progress where teaching assistants are trained and effectively trained to deliver specific support programmes, alongside well-planned lessons - as this research acknowledges.
"And the DISS study found that 14-year-olds who worked closely with teaching assistants were less distracted... followed instructions, were more independent, confident, motivated and likely to complete work."
He added that the research made no allowance for teaching assistants' experience, training or qualifications nor whether the school was high- or low-performing, the extent it had been remodelled or whether the teacher or teaching assistant were teaching as a team or separately.
Head of education at the public service union Unison Christina McAnea said: "Unison has been calling for better pay, training and more paid time for teaching assistants to do their jobs, for many years.
"Teaching assistants are not substitutes for teachers, but what they can do, given the right training and support, is help children with special needs to get the most out of school."
The findings of the study are being presented at the British Educational Research Association conference in Manchester on Friday.