The amount spent on textbooks and teaching equipment in Essex’s secondary schools has dropped by more than 30% in the last five years, it has emerged.
Figures show the amount spent per pupil in Essex County Council-maintained schools has fallen from £228 in 2012-13 to £153 in 2016-17.
The National Union of Teachers (NUT) said schools were increasingly asking parents for contributions.
The council said schools “have complete autonomy” over their budgets.
Spending on “learning resources” in schools includes book costs, trips and teaching materials.
The total amount spent on learning resources dropped 74% from £3.6m in 2012-13 to £931,000 last year, the figures, released under the Freedom of Information Act, reveal.
However, year-on-year comparisons are misleading because the number of county council-maintained schools has dropped from 17 to seven during the same period.
The average amount spent per school dropped 37.5% between 2012-13 and 2016-17, from £212,824 to £133,028.
Peter Malcolm, the Essex representative of the national executive of the National Association of Head Teachers, said: “There’s no way the secondary sector can survive in this situation.”
He said schools faced a combination of additional responsibilities, such as monitoring pupil mental health, “more curriculum initiatives with very focused outcomes” and “inflationary pressures” – without the extra funding they need.
“There is a real squeeze on the school budgets.”
At many schools, he said, school trips were often cancelled if 90% of parents did not make “voluntary contributions” to cover the costs.
Jerry Glazier, NUT national executive member in Essex, said: “Schools are suffering serious cuts.”
He said some schools in the county were looking to reduce staff numbers or non-core areas of the curriculum.
“What that means is the amount of flexibility that schools have has been significantly diminished and they are having to resort to expecting pupils and parents to provide more of the basics of education,” he said.
“This particularly affects children from disadvantaged backgrounds.”
The Department for Education was approached for a response but is yet to respond.
Ray Gooding, the county council’s cabinet member for education, said: “Ultimately, it is up to the governing bodies of schools to decide how their budgets are spent.
“That said, we are committed to ensuring all pupils in Essex receive the best possible education and closely monitor the county’s schools.
“We recognise there have been real terms budget reductions as a result of the increased costs faced by schools and are making representations to government.
“However, with more than nine in ten Essex schools currently rated as good or outstanding by Ofsted, we are confident that schools in the county are making very effective use of the budgets available to them.”