Research by a supply teacher has found that there is little incentive for short-term teachers to raise their performance although school managers are concerned about the quality of their work.
Jennifer Spratt, who looked at how two secondaries in the north-east handled supply staffing, concludes: "The absence of training, of structured support and of open evaluation must have had implications for classroom performance."
One supply teacher said: "If you don't like asking people, if you can't cope with a disorganised life, if that hassles you, you shouldn't be a supply teacher."
A supply probationer concerned about the lack of communication in her school went further: "You're just a kind of prostitute really, out to take any work. No one asks your opinion or anything, really they're not interested at all. And they don't tell you anything at all."
Ms Spratt, whose study led last year to a master's degree in education from Aberdeen University, says that schools receive too little information about teachers on the supply list. Because there is such wide access to the list, it does not contain confidential details such as qualifications, experience or referees' reports.
A school's senior managers therefore operate informal systems of quality control, by monitoring performance and reselecting effective teachers. But this could led to insecurity, she says, especially as the only guide to whether a supply teacher had performed well was whether they were asked back. P> One depute headteacher said: "The cop-out is just nae to use them again."
A teacher said: "You feel you're only as good as your last job. You've got to make the effort, the wee extra things."
Ms Spratt recommends that heads should have access to confidential information on the supply list and be obliged to state when they are unhappy with a teacher's performance so that problems can be addressed. "Perhaps the best support for a struggling supply teacher would be an experienced supply teacher."
The lack of back-up is "in sharp contrast" to the extent the system depends on supply staff. But the majority of those filling in for a class teacher on short contracts enjoyed their work and were confident about their abilities.
They appreciated the freedom of flexible working hours. One said: "I've got three young children, so I don't want the responsibility of full time, of writing reports, parents' evenings or curriculum development. At the end of the day you're not involved in the politics that happen in schools and you're not going to any meetings."
The McCrone report called on the Executive to review the use of supply cover, including the possibility of "standing teams" of permanent peripatetic teachers. It also wanted a continuing professional development plan for every teacher.
Ms Spratt's research found that short-term supply staff generally fell outside any provision for staff development.
Untrained, Unsupported and Underperforming? The complexities of employing supply teachers by Jennifer Spratt is available, price pound;5, from the Centre for Educational Research, Department of Sociology, University of Aberdeen AB24 3QY.