Education standards across England are in "serious danger" because of severe budget cuts, headteachers have warned.
Schools across England are being forced to cut courses, equipment and books, increase class sizes and make redundancies because of significantly reduced budgets, according to the Association of School and College Leaders (ASCL).
The ASCL accused the Government of "asking the impossible" by demanding that schools improve standards, without giving them the money and resources to do so, ahead of a conference of headteachers in Birmingham later today.
A survey of ASCL members found the majority believe cuts will significantly affect standards.
Research has shown that England's schools will have to make real-terms cuts of around 8% over the next five years, because of extra costs that they will have to meet from their existing budgets, ASCL said.
In his speech to the conference, ASCL president Allan Foulds is expected to say that the combination of funding cuts with a teacher shortage poses a serious threat to schools and colleges.
In a separate report from ASCL and the Policy Exchange think-tank it was suggested that the shortage of teachers could be addressed by allowing them more flexibility to come in and out of the classroom throughout their careers.
It claims that more flexible working, including career breaks and secondments, could encourage more people to stay in teaching especially women.