By David Spereall
In a statement, OGAT said it was “deeply disappointed” the NEU had turned down its proposals to solve the dispute.
A spokesperson said: “Resolving the significant disruption to children’s education remains our highest priority.
“We’ve therefore consistently prioritised meetings and discussions, and have offered a number of solutions and refined proposals to our union colleagues.
“While NASUWT has been amenable to them, unfortunately the NEU has not been as positive and we have been unable to make the same progress as a result.”
Andy Wroe, whose son attends Outwood Academy in Sheffield, told the BBC the situation was “not good enough”.
“The kids’ education is suffering, their friendship groups are suffering, and I don’t feel it’s fair,” he said.
“As a parent, we just want the right thing for the kids. I don’t mind the teachers protesting – they’ve a right to do so – but we need to find a resolution because the kids are suffering.
“They just need to talk and realise there are a lot of children in the middle who are nervous, disrupted and worried.”
Further talks between the union and academy bosses are due to take place next week, with mediators from the Acas arbitration service involved.