Labour and the Liberal Democrats have pledged multi-billion pound cash injections into the education system as the campaign trail hits the classroom.
On a visit to the south-west of England, Lib Dem leader Tim Farron warned that a landslide victory for Theresa May will "cut our schools to the bone".
He said: "Two-thirds of schools are planning to lay off at least one teaching post in the next two months.
"There needs to be a fully-costed response to build a future for all of our children so that we can have decent education and be confident in that."
Mr Farron promised an extra £7 billion spending boost for schools as well as a five-year package to reverse cuts to frontline budges - money, he says, will come from his party's policy of staying in the European single market.
"You cannot have strong, well-funded schools and hospitals with the most extreme version of Brexit.
"My priorities are to support out schools, our health and social care - to do what's right for our country, not to appease the Ukip wing of the Tory party."
Jeremy Corbyn meanwhile told reporters the Conservatives have been "starving schools of funding" and will hike corporation tax to inject £4.8bn of additional funds into education.
The Labour leader, who launched one of the "pillars" of his campaign in Yorkshire, announce an "inclusive, fair and costed" hike that will see corporation tax increase from 19% to 26% by 2021.
Angela Rayner, shadow education secretary, said: "It's truly frightening that school budgets are being cut for first time in 20 years.
"We're going to see a generation of our children being held back."
Announcing the first stages of Labour's National Education Service, she said, if elected, "every child - whatever background - will be given an opportunity to unlock their full potential."
In March a report by The Education Policy Institute warned that schools are facing a major funding crisis with secondary schools in line to lose the equivalent of six teachers' salaries in funding.
The National Association of Head Teachers' general secretary Russell Hobby said: "This General Election is a make or break moment for education. School budgets are at breaking point right now.
"More money for schools is absolutely vital. Whoever forms the next government needs to fund education fully and fairly, reversing the £3 billion of real terms cuts schools are facing."
To fund the Lib Dems' education plan, party leader Tim Farron said they would reverse tax cuts like corporation tax and the marriage tax allowance and said more details would be released in the manifesto.
Liberal Democrat Shadow Education Secretary Sarah Olney said her party's pledge of an extra £7bn of funding would ensure no school and no child loses out.
She said: "We will reverse crippling Conservative cuts to school budgets and invest to ensure every child has the opportunity to succeed."
Tory Treasury minister David Gauke criticised both pledges saying Labour "can't deliver any of this - they're just made up promises on the back of nonsensical spending plans".
"The Lib Dems are no better and won't even tell people about the tax rises they would bring in," he added.