All secondary pupils in Scotland should be given ID cards in an effort to stamp out bullying, according to a teaching union.
The union said pupils were bullied to hand over meal cards
The Scottish Secondary Teachers' Association (SSTA) says many schools already have card systems in place for school lunches and libraries.
It believes adding a picture would stop pupils missing meals because they have been bullied into handing over cards.
However, the Green Party described the proposal as "deeply troubling".
The SSTA's general secretary, David Eaglesham, said the time had come for photographic identification to be added to the cards used to access school facilities.
"Introducing photo ID cards will help bring an end to bullying over use of 'cash free' cards for school meals, will assist with access to school bus services and, ultimately, can be used to add security to school examinations," he said.
"SSTA members report frequently that young people are bullied into handing over their cards for school meals to others, thus leaving them without their meal entitlement.
"With non-identified cards this will remain a problem. If photo ID is introduced widely, then the problem will dramatically reduce."
He said that introducing such a system would also help prepare young people for "the realities of identity management in the 21st Century".
However, Green MSP Patrick Harvie said the suggestion was troubling.
"We should be preparing young people for the reality of defending their privacy and civil liberties against ever-more intrusive government systems," he argued.
"We've heard proposals for airport-style scanners and random drug testing in schools, fingerprinting is already in place in some schools. There's a risk of creating environments which feel more like penal institutions than places of learning.
"These ID cards will do absolutely nothing to address the causes of bullying. Instead they will teach the next generation that an ID card culture is 'normal', and that they should have to prove their entitlement to services."