A literacy programme led by teaching assistants that aimed to help pupils who struggle with reading has had no impact, according to researchers – contradicting previous findings.

An independent evaluation by Education Endowment Foundation (EEF) explored Switch-on, a 10-week Nottinghamshire County Council scheme where teaching assistants were trained to deliver an intensive one-to-one literacy intervention for pupils having difficulties with reading .

It was made up of short reading sessions that aimed to support the pupils to become more confident and independent in their reading ability.

An earlier and smaller EEF-funded trial of Switch-on involving 19 schools showed that it had delivered an average of three months’ additional progress for pupils struggling to read at the transition between primary and secondary school . The EEF funded a bigger trial to find out if these results could be repeated at a larger scale in 184 schools across England.

But independent evaluators from the National Centre for Social Research found that the children who received the Switch-on intervention in this larger trial made no more progress than the children in the control group.

However, the EEF said the difference in results could be because the training model was altered so that the programme could be run in a larger number of schools.

EEF senior programmes manager Emily Yeomans said: “Sometimes an exciting initiative can work well when it is run in a small group of schools. But it can be hard to get the same results applied on a much bigger scale or across a system.

“While it is disappointing that we haven’t seen the same impact on literacy grades for Switch-on in this bigger trial, we know that training teaching assistants to deliver structured, high-quality interventions can have a great impact on learning."

The EEF will now discuss with the Switch-on team options for developing and testing an alternative model that can be delivered in many schools across the country, but with the same positive effects of the smaller trial. Ms Yeomans said: "This new report gives us important new evidence on how best to do that.”

The foundation has also published the results of an evaluation into whether a foreign language learning programme helped general literacy skills. It was based on 46 schools that were teaching French with a linked English literacy curriculum developed by the Education Development Trust (formerly CfBT).

The programme lasted for three half-terms. French classes were 45 minutes long and the linked activity required an additional 15 to 30 minutes of English class time per week. Teachers were provided with detailed lesson plans and three days of training in delivering the curriculum.

But independent evaluators from UCL's Institute of Education found no evidence that it had a positive impact on English outcomes beyond the impact of normal foreign language provision. However, the results may be unreliable due to problems with collecting data from some of the participating schools, the EEF said.