A union leader has warned that the funding crisis facing schools across Sheffield was untenable - and many are at breaking point.
The National Union of Head Teachers' Rob Kelsall said 131 out of the 154 schools in the city face funding cuts under the Government's new national funding formula.
He said there has been a sharp rise in the number of pupils being taught in super-size classes, vital support for children with special needs being taken away and others considering shortening the school day or moving to a four-and-a-half day week.
Mr Kelsall, the union's national secretary for organising and campaigns, called on schools and politicians from all parties to unite to 'end the crisis'.
He said: "Schools across Sheffield are at breaking point.
"Government cuts to school budgets have been unrelenting in the last few years and headteachers are saying that enough is enough.
"We are seeing a sharp rise in the number of pupils being taught in super-size classes, vital support for children with special needs being taken away and some schools even having to close early and move to a four and half day week in order to make the books balance.
"A total of 131 out of 154 schools in Sheffield that we’ve analysed, face funding cuts.
"The situation is untenable and we are calling on politicians on all sides to join with us and end this crisis right now."
The NAHT is hosting an education summit in Sheffield to discuss the funding situation next week.
The Star revealed Sheffield is the worst funded out of all the major cities in England and headteachers have warned of mass redundancies as they struggle to keep schools operating to their current standards.
The Department for Education said schools in the area will attract an increase in funding of 6.6 per cent - equivalent to £20.4 million - when its new NFF is implemented in full by 2020/21.
But education leaders said the increase is not in line with inflation and rising costs.
The Star has launched a campaign calling for fairer funding for schools which has received the backing of all six city MPs.
Mr Kelsall added: "The children and young people of Sheffield and throughout Yorkshire are our future. They deserve a first class education service.
"Investment in our schools should never be seen as a burden on the taxpayer. Without the skills for the economy of tomorrow, how will the UK survive and prosper in a post-Brexit economy?”
The summit on Friday June 15, runs from 3.30pm - 5.30pm. To attend register by emailing firstname.lastname@example.org