Theresa May has launched an attack on Labour leader Jeremy Corbyn for sending his son to a grammar school.
At Prime Minister’s Questions she said: “Typical Labour, take the advantage and pull up the ladder behind you.”
Mr Corbyn had accused the government of finding money for Mrs May’s grammar school “vanity project” while cutting funding for other schools.
The Labour leader’s son Ben went to a North London grammar school although Mr Corbyn was reported to be against it.
The issue is said to have led to the break-up of Mr Corbyn’s second marriage in the late 1990s, with his then wife Claudia insisting that the child should not attend a local Islington comprehensive school.
During Wednesday’s clashes in the Commons Mr Corbyn accused Mrs May of “betraying a generation of young people by cutting the funding for every child” with a new funding formula for schools in England.
“Children will have fewer teachers, larger classes, fewer subjects to choose from and all the Prime Minister can do is focus on her grammar school vanity project that can only ever benefit a few children.”
He said the government found no extra money in the Budget for schools but offered £320m for Mrs May’s grammar school project.
The prime minister said the funding formula would be fair to all but stressed that it was still at the consultation stage and had not been finalised.
She then rounded on Mr Corbyn and his front bench team, listing those who attended a private school or a grammar school.
“He sent his own child to a grammar school, he himself went to a grammar school,” she added, pointing at Mr Corbyn and accusing him of hypocrisy.
Analysis by BBC Political Editor Laura Kuenssberg
Theresa May’s government has form on changing its mind when it’s clear a policy is heading into a political quagmire. After all, it was only seven days ago the chancellor junked the planned tax rises for two million or so self-employed people.
Is there another U-turn in the offing? Parents and schools in different parts of the country are cross. Labour, some Tory backbenchers and local councillors around England are riled. And accusations are building again that the Tories would be breaking another manifesto commitment – their 2015 promise to protect the amount of cash that is spent on each pupil at school.
There is no question that school budgets are already under a lot of pressure, with many schools having to cut back because money is already short.
One of the tough things for the government is that they are hoping to push through a reform where there will be plenty of financial losers at a time when cash is already short, and falling in real terms. But are ministers ready to give up this time? No, or perhaps, not yet
Mr Corbyn insisted he wanted a “decent, fair opportunity” for every child in every school.
Mrs May told him: “He says he wants opportunities for all children, he says he wants good school places for all children – then he should jolly well support the policies we’re putting forward.”
The prime minister went to a grammar school in Oxford, Wheatley Park, which became a comprehensive while she was there.
The government is planning to overturn a long-running ban on opening new grammar schools, which select pupils by ability, but says it has no plans to bring back the 11-plus exam.
Education Secretary Justine Greening is consulting on a new formula for schools in England, to address what it calls the “unfair, opaque and outdated” distribution of money.
It says more than half of schools will receive a cash boost and protections will be put in place to ensure no school loses more than 6% of their budget in real terms.
But it has sparked criticism from head teachers and governors, who have said it does not take account of rising costs and will leave some schools desperately short of cash.