From sponsored bike rides to tombolas and auctions, fundraising drives are part of the fabric of our lives. They can help to strengthen social ties as well as raising money – as when parents bond with teachers across tables loaded with jumble or cakes. Funds raised in this way have long provided valuable extracurricular extras for schools, helping to pay for trips or special projects such as pantomimes or gardens. And there is no reason why communities should not seek to add to the resources supplied by the state.

What they cannot do, and should not be forced to attempt, is compensate for the state’s shortcomings. When schools are forced to fundraise for essentials such as pencils, no amount of the goodwill associated with donations can disguise the underlying problem. Yet an investigation by the Guardian shows that the line has been crossed decisively and that such drives are becoming routine. About 100 schools in England have Amazon wishlists including such items as erasers and glue; another 10 are asking for soap, vacuum bags or other cleaning products. Last month, one Surrey headteacher revealed that cuts have led to her helping to clean her school’s toilets and serving in the canteen. Evidence of the damaging effect of cuts on special needs provision and in narrowing the curriculum is widespread. Last month 7,000 headteachers united to warn of a “funding crisis” in a letter to parents sent after education secretary Damian Hinds refused to meet them. They are right.

Mr Hinds has made clear his intention to seek increases to school budgets in the next spending review, and his recruitment and retention strategy will fail unless funds are secured. That he recognises the problem is a relief. But often-repeated statements by ministers to the effect that school funding is at its highest-ever level are a nonsense. Research from the independent Institute for Fiscal Studies found that between 2009-10 and 2017-18, total school spending per pupil in England fell by 8% in real terms (compared with 5% in Wales). It is insulting to tell parents and pupils, as well as teachers, to distrust the evidence of their own eyes.

Fundraising may fill the holes in some school budgets, but it exacerbates existing inequalities. Successful fundraising, after all, relies on donors with spare cash. Many families will struggle to support such drives and may feel excluded from activities. In an already divided society, children of poorer parents will be disadvantaged relative to their peers because their schools are unable to tap families for donations as those in richer areas can. In many places, staff are already dipping into their own pockets to help pupils hit by the broader impact of austerity, buying them not educational materials but food and underwear.

A specialist educational fundraising platform, RocketFund, has been used by 400 schools across the UK. RocketFund was a government-sponsored start-up, and it is unsurprising that Conservatives are enthusiastic about an enhanced role for philanthropy in our school system. This would make state schools more similar to private ones, and is in keeping with the “big society” ethos that David Cameron once espoused, promoting volunteerism over statutory services. The belief that rips in the social safety net can be patched up by individual generosity has been thoroughly disproved by the punitive cuts in public spending that his government imposed and his successor has continued.

Teachers or parents who spend their weekends crafting online fundraising campaigns to benefit other people’s children deserve thanks. They are contributing to the cost of educating the next generation. There have been admirable, even inspirational efforts by individuals and groups. But such efforts will not bridge the gap everywhere, and should not be relied on anywhere. Charity cannot compensate for austerity.