Children struggling with reading and maths make significant progress when given as little as 30 minutes' individual attention a week by a teaching assistant, research has revealed.
Primary school students who received two 15-minute maths sessions a week made three months more progress over the course of a year than their classmates, according to a study published today by England's Education Endowment Foundation (EEF).
Children who were helped with their reading for 20 minutes a day for just 10 weeks made similar progress. One school reported that the reading ages of its students leaped by as much as four years in 10 weeks.
The positive findings come after previous large-scale studies declared that teaching assistants made no difference to student attainment and could have a negative impact when working with lower attaining children.
There are now 232,000 teaching assistants in England, according to government data, compared with 442,000 teachers. Teaching assistants receive an average salary of pound;17,000, meaning that about pound;4 billion is spent each year on their pay.
In a report published in May last year, the Reform thinktank argued that schools should reduce their numbers of teaching assistants because the evidence showed little impact on student progress.
Peter Blatchford, professor of psychology and education at the University of London's Institute of Education, ran a five-year study of 20,000 teachers and teaching assistants. It found that teaching assistants did not improve children's learning because they tended to be used in classrooms to support low-attaining students in small groups, meaning that the children spent less time with a qualified teacher.
But Professor Blatchford said this did not mean that assistants had no value, simply that they were not valuable if used as substitute teachers.
"It is very encouraging to know teaching assistants are being given a positive role, despite the fact that our research has been used by some to query the use of teaching assistants in schools," he told TES this week. "I've always been of the view that it can't be beyond the wit of people to find a way for an extra person in school to add value to teachers' work."
The new evidence supporting the use of teaching assistants focused on two specific programmes: the 10-week Switch-on Reading scheme for 11-year-olds and the 30-week Catch Up Numeracy initiative for seven- to 11-year- olds.
Randomised controlled trials showed that students receiving support from a teaching assistant made the equivalent of three months' additional progress over a year. The lowest-achieving children made the equivalent of five months' progress in reading.
Dawn Chivers, assistant headteacher of the Brunts Academy, a secondary school in Mansfield that uses the Switch-on Reading scheme, said: "One student arrived with a reading age of 8 and now has a reading age of 12, which is where he should be. Another began with a reading age of 6.3 and now has a reading age of 8, after 10 weeks.
"That is a tremendous boost in a short period. The children in our pilot group made significant gains with Switch-on Reading and we couldn't run this level of intervention without teaching assistants."
The findings come from two of the first six randomised controlled trials run by the EEF, a government-funded research charity that is attempting to find the best ways for schools to close the achievement gap between children from rich and poor homes.
Dr Kevan Collins, chief executive of the EEF, said the evaluations were the first step in creating an evidence base to improve results. "In the past, many schools have struggled to train and support teaching assistants in ways that benefit children, particularly students from disadvantaged backgrounds," he said.
"These studies suggest some promising ways to change that. The results show that when a group of schools come together to test something, we can generate knowledge that is hugely valuable to all schools."
Graham Sigley, deputy director of Catch Up, said the trial reinforced a "key message" that teaching assistants, when trained and supported, could make a significant difference.
Christine Blower, general secretary of the NUT teaching union, said: "Many teachers acknowledge the work done by teaching assistants and appreciate the support they afford."
A UK Department for Education spokeswoman said it was "vital" to close the gap between disadvantaged children and their peers. "We know that teaching assistants, when properly trained and deployed, play an important role in helping to improve learning," she added.