The threat of cuts still hangs over the programme to build new schools in England, with ministers refusing to confirm spending plans.
Education Secretary Michael Gove was pressed repeatedly in the House of Commons to end the doubt over school rebuilding projects.
Mr Gove told MPs that building plans remained under review.
The construction industry has warned that firms will be shut down if school building projects are axed.
The £55bn Building Schools for the Future programme has been renovating and rebuilding schools across England.
Last autumn saw the biggest opening of new schools since the Victorian era.
But there have been unresolved questions about whether the building programme is going to be stopped by the Conservative-Liberal Democrat coalition.
Construction industry organisation, the Construction Products Association (CPA), says the school building programme is worth £10bn a year - and has helped to protect recession-hit businesses.
The CPA's economics director, Noble Francis, says the government should recognise the value of the investment to the wider economy.
And he warned that if school projects were cut, the negative impact on construction firms would deepen until at least 2014, forecasting the closure of firms and the loss of jobs.
MPs called on ministers in the coalition government to clarify urgently whether plans that have been announced will still go ahead - or whether they will be scrapped by spending cuts.
Alex Cunningham, MP for Stockton North, said there had been no new secondary school built in his constituency for 40 years - and that £5m had already been spent on rebuilding plans.
He called for information on whether plans for new schools were now going to be stopped.
Another MP told of a school propped up by scaffolding, where a local community was waiting to hear whether building plans would go ahead.
Mr Gove, taking questions alongside Children's Minister Sarah Teather, repeatedly fended off questions about school building projects, saying that funding plans were under review.
The education secretary said the government wanted better value for money from building plans - and that too much had been spent on consultants.
Shadow Education Secretary Ed Balls also pressed the coalition partners on spending, challenging ministers on how promises about the pupil premium would be delivered.