. "I think most teachers intuitively recognise that. There are real signs that some schools are using TAs in a much more structured way and those schools are seeing an impact, but they are the minority."
He added that there was strong evidence that TAs working one-to-one or with small groups of pupils to give intensive support for as little as 30 minutes a week could help pupils to make an additional three to four months' progress over a year.
The EEF guidance, which is aimed at headteachers, suggests that teachers and TAs should take turns to work with different groups of pupils. TAs could also demonstrate the equipment to be used in a lesson while the teacher is talking, it adds.
But without action to ensure that TAs were used more effectively, their role could be under threat, Dr Sharples said.
"I think that the widespread use of teaching assistants could be at risk if something is not done. They can make a significant difference; the report is about unlocking their potential."
Jon Richards, national secretary for education and children's services at Unison, said that many of the public sector union's members were "pushed into roles they are not trained to do" and frequently missed out on CPD.
"There is increasing quality research that shows well-trained teaching assistants can make a positive difference," he added. "We need to share more best practice about how they are trained and deployed, as it is in no one's interest to neglect the training needs of teaching assistants."
A TA at a Manchester secondary, who did not want to be named, said the role had become more prominent in her school but some teachers were not sure how to make the best use of support staff.
"I do love this job," she added. "I thought about being a teacher, but after seeing the pressure they are under to tick boxes, I was put off a little bit. Some people do this as just a job, just for a bit of money. But I think it is more than that: it's a vocation. It's about benefiting the students involved."
`Teaching assistants don't just sit around'
Andrew Truby, headteacher of St Thomas of Canterbury School in Sheffield, says teaching assistants are used to run "pre-learning" activities before lessons at the primary.
"We have children coming in at 8.30am for extra sessions in a maths programme, which the teaching assistants have been trained to give. That has had a massive impact," he says.
"We have some special educational needs teaching assistants who work with children with complex needs. We don't have teaching assistants just sitting around watching teachers teach.
"We also have a couple of TAs who make sure every classroom is well organised and stunning, with high-quality displays, so that children's jaws drop when they walk in."