Parents across England are to hold a day of action to raise concerns about cuts to school funding.
Thousands of people are expected to take part in local protests and events across the country this Friday, campaigners said.
The action is aimed at highlighting the issue of school cuts to all those campaigning in the General Election, according to organisers Fair Funding For All Schools.
The parent-led group is calling for parties and candidates to commit to addressing the funding shortfall.
Campaign co-founder Jo Yurky said: “The significant point about this is it is people who do not normally do this sort of thing.
“This is ordinary parents picking up their children and going to do this picnic protest. It’s ordinary people doing extraordinary things, people who have been moved to take action because they are so concerned about cuts to our schools.”
Schools in England need to make £3 billion in savings by 2019/20, according to Government estimates, the National Audit Office (NAO) has said.
The latest move by campaigners comes as the main political parties set out their stalls on education funding.
The Conservatives have said that they will increase the schools budget by £4 billion by 2022, which it says represents more than a real terms increase for every year of the next parliament.
Labour has said it will fund a National Education Service, with almost £5 billion extra pumped into the English school system by 2022, by raising corporation tax from its 19% rate to 26% by 2021/22.
The Liberal Democrats have said schools and colleges will receive a £7 billion spending boost if they win power, including £3.3 billion to protect per-pupil funding in schools.
In a statement, Fair Funding For All Schools said that schools are already feeling the impact of a squeeze on budgets, and that it wants to see per-pupil funding protected in real terms over the lifetime of the next parliament.
It also wants assurances that no school will lose funding as a result of a new national funding formula.
More than 40 events, which are expected to be attended by parents and pupils as well as teachers and school governors, are due to take place on Friday.
Ms Yurky said that the events are being used to maintain pressure on political parties and to make parents’ voices heard.
She added: “As a result of the brilliant campaigning by parents across the country, all parties now accept the need for more school funding.
“We’ve seen major concessions in the party manifestos but, sadly, not all of them go far enough.
“At the very least, we need pupil funding to be protected in real terms over the next five years.
“Anything that falls short of that is unacceptable.”