New teachers have often struggled to find sufficient work to gain them permanent employment rights.
But now, teaching unions in Scotland claim that more and more councils are deliberately trying to create a break in teachers' employment so that they cannot claim a year's continuous service and the accompanying right to be regarded as permanent supply teachers.
Hugh Donnelly, Glasgow local area secretary for the Educational Institute of Scotland, claims that Glasgow City Council has shifted its employment policy over the summer because of financial pressures. He claims the council is, for the first time, taking action to break contracts to prevent teachers accruing employment rights - a "cynical legal move", as he describes it.
A spokeswoman for Glasgow City Council said: "A number of factors in Glasgow this year - continued falling school rolls, school closures and mergers, and the current financial climate - have meant that there has been a reduction in the number of supply vacancies at the beginning of term.
"All of Glasgow's permanent contract supply teachers have been found posts across the city and it is inaccurate to suggest that we are terminating any temporary contracts."
But Glasgow is not the only authority under fire. Paisley North MSP Wendy Alexander has taken up the cause of temporary supply teachers in Renfrewshire who claim they, too, are being deliberately denied the chance to accrue permanent employment rights.
Councillor Lorraine Cameron, convener of Renfrewshire Council's education policy board, said: "For Renfrewshire to hire all the probationer teachers who have worked with us over the past two years would require around 15 per cent of our teaching workforce to leave.
"Renfrewshire is no different to many other authorities. If there aren't permanent posts available we can't simply create those. It's worth pointing out that over half of its probationers in the past two years have been given temporary supply employment."
"Having worked with Renfrewshire Council as supply for two years, I would have expected to now be permanent staff. The criteria for gaining permanency is one full year with no more than 10 days' continuous break. However, they count a break as not giving you work. I applied for permanency last year but they refused it as they stated there were too many breaks in my service; they believe that my not being given work, despite calling every day ready to work, counts as breaks in service. "This year, I have worked the full academic year, with the exception of the last week of term (this again is not for the lack of willing). I phoned the council and pursued the issue of temporary to permanent once more and yet again my rightful request was beat down. I have now been told that I must be back one day within the first five days in order to meet the criteria. There is, most frustratingly, not a minute hope that I will meet this demand as it appears that they will not give me or others in the same predicament any work."
"Having completed by probationary year in a primary school in Paisley, I was asked to return to work as a supply teacher to cover a maternity leave. I remained in the same class for nearly a full year as a supply teacher. During the last week of term, I worked in another two Paisley primary schools. "During the summer holidays, I made contact with the council nearly every day with regards to supply work in the new term. As I had almost completed a full year as a supply teacher, I would have been eligible for permanent supply had I been offered work at the beginning of term. Needless to say, I have not been offered any work. However, as a qualified Catholic teacher, I have been appalled to hear that this week, non Catholic-qualified teachers have been placed in Catholic schools."