Protests have taken place in colleges around England over government plans to axe the education maintenance allowance next year.
The government plans to scrap the scheme in England, which is aimed at encouraging poorer pupils to stay in education, from September next year.
Supporters of the EMA, which is worth up to £30 a week, say it stops thousands of students dropping out.
However, ministers say it is an inefficient scheme.
Chancellor George Osborne announced plans to axe the scheme in the spending review, saying it had very high "dead weight costs".
There are no plans to cut the similar schemes that operate in Wales, Scotland and Northern Ireland.
The Department for Education plans to replace the scheme with targeted support for pupils who it says "face genuine financial barriers to participation".
Several studies show the EMA, introduced by Labour, as a key factor in increasing and maintaining the number of young people taking part in education.
Recent research suggests students on EMA miss fewer classes and are more likely to stay on in college than wealthier students, despite the fact they tend to have poorer prior attainment.
The EMA is effective because it is only paid if recipients attend all their classes. Colleges and schools withdraw the week's money if pupils miss class without a good reason.
And many pupils depend on it to fund their transport, books and even basic living costs.
However, School Minister Nick Gibb cited research in which 90% of EMA recipients questioned said they would stay in education even if they did not receive the allowance.
He said a "very generous" support fund would be created and targeted at the remaining 10%.
A report by the centre-right Policy Exchange think-tank in 2008 called for allowance to be axed, saying it had insufficient impact on participation.
Save EMA campaign organiser James Mills said many students would drop out of education if the scheme was scrapped.
"When there were problems with the administration of the allowance a couple of years ago I remember lecturers at my college bringing in bags of shopping for pupils who did not get their money," he said.
Seven trade unions - including the UCU, the NUT, Nasuwt and the ATL - have been joining the protests, which were scheduled for lunchtime in about 100 colleges around England.
In some cities such as Birmingham and Leicester, and parts of north-west England, as many as four-fifths of students receive the allowance.
Ahead of a protest at the City of Bath College, principle Matt Atkinson said axing EMA would lead to pupils dropping out.
"Where you have got colleges that are serving rural areas, a lot of these young people are using EMAs to actually get to college," he said.
"For young people from disadvantaged backgrounds this is a significant contribution to the household income."
General secretary of the UCU lecturers' union Sally Hunt said the EMA was a vital lifeline for many students.
"Withdrawing the EMA will hit some of the poorest and most vulnerable people in our society, as well as the colleges that are there to serve them."
Christine Blower, general secretary of the National Union of Teachers, said if the EMA was axed it would be a disaster for social justice and for the economy.
"Education is the major factor in social mobility, ending the EMA will mean that many students from less well off backgrounds will simply not be able to countenance continuing with further education."
General secretary of the Nasuwt teaching union Chris Keates said: "The abolition of the EMA is a direct attack on the futures of thousands of young people across the country. They have a right to be angry and to use the democratic process to influence elected representatives to oppose these changes."
ATL general secretary, Dr Mary Bousted, said: "Cutting the EMA will hit the most disadvantaged students hard and make it impossible for some to stay in education."
The Association of Colleges shares the concerns and its chief executive Martin Doel has written to Michael Gove asking for him to rethink the plans.
Mr Gibb said: "Given the economic climate, the state of the public finances and the very difficult decisions we have had to make across government, it is only right that we should find a better, more effective way of targeting support to those young people who really need financial support to continue in education."