Parents are being asked to pay for textbooks, art materials and to buy tickets for school plays and sports events, as schools attempt to plug funding gaps, a survey suggests.
It also indicates around one in six are asking mums and dads for cash to help with the running of their child's school.
One teacher told teaching unions that pupils were being asked to take photos of homework on their phones in order to save money, while another said they had to cancel a gymnastics lesson as the hall was being leased out.
The findings, by two teaching unions, come amid concerns from school leaders and teachers about growing funding pressures in England's state schools.
Ministers have argued funding is at record levels.
The survey, which questioned almost 1,200 members of the National Union of Teachers (NUT) and the Association of Teachers and Lecturers (ATL), found three in four (76%) said their school's budget has been cut this year, compared to last, while 93% said they are pessimistic about their school's funding over the coming three years.
One in six of those polled (17% of those working in primaries and 16% in secondaries) said their school had asked parents for money to help with school funding.
Most said a sum of money was not specified but 14 people said their school was asking for more than £20 a month.
Around half (49%) of union members said their school had asked parents to pay for specific items.
Most commonly, mums and dads were asked to pay for tickets to school concerts and sports events. There were also requests for parents to pay for art and design materials and textbooks, as well as library books, IT and sports equipment.
A London teaching assistant said: "To save money children are often asked to take photos of homework on their mobiles."
Just over two-fifths (44%) said their school is renting out buildings, around a quarter (26%) said school grounds are leased out, 5% said their school is renting out its car park and 6% said their school accepted advertising.
A primary school teacher in Essex said: "I had to cancel gymnastics lessons due to our school hall being leased out for educational conferences during the day."
The poll, published ahead of the unions' annual conferences, also found 50% of those surveyed said their school has bigger class sizes than last year while 73% said their school has cut spending on books and equipment.
ATL general secretary Dr Mary Bousted said: "The Government needs to sit up and listen. Schools are already struggling to make ends meet and children are already losing out.
"But Government underfunding means this will get much worse, since in two years' time schools will have to make savings of more than £3 billion a year.
"Unless the Government finds more money for schools and fast, today's schoolchildren will have severely limited choices at school and children from poorer families will be even further disadvantaged because their parents may struggle to provide the resources schools can no longer afford."
A Department for Education spokeswoman said: "The Government has protected the core schools budget in real terms since 2010, with school funding at its highest level on record at almost £41 billion in 2017-18 – and that is set to rise, as pupil numbers rise over the next two years, to £42 billion by 2019-20.
"We recognise that schools are facing cost pressures, which is why we will continue to provide support to help them use their funding in cost effective ways and make efficiencies.
"This includes improving the way they buy goods and services and our recently published School Buying Strategy is designed to help schools save over £1bn a year by 2019-20 on non-staff spend."
Schools must make clear that parents are not obliged to make contributions, she added.
:: The survey, conducted last month, questioned 1,177 NUT and ATL members working in England's state schools.