Philadelphia has halved staff turnover this year by drafting in a cadre of teacher-coaches to support new recruits.

According to school chiefs, 65 experienced teachers were withdrawn from the city’s classrooms last year and put through intensive training. Each was then assigned a caseload of about 17 new recruits last September.

The scheme has helped the seventh-largest education authority in the US to boost retention of new staff to 92 per cent from the low 80s a year ago, said recruitment and retention director Tomas Hanna.

Coaches have been on hand to advise and give demonstration lessons for Philadelphia’s 1,300 new staff, he said. Advice has also been made available on how to contact parents and deal with the mountains of paperwork faced by staff.

Mr Hanna said: “It’s over-the-shoulder support. New teachers have told me that were it not for their coach they would probably have left.”

USeducation authorities are increasingly turning to staff mentors to combat teacher attrition.

Turnover is particularly acute among novices, who are often pitched in at the deep end with tough classes which have been spurned by senior colleagues.

“They feel they’re in a sink-or-swim environment,” said Tom Carroll of the National Commission on Teaching and America’s Future.

Some 46 per cent of new teachers leave within five years and a third within three, according to research by the University of Pennsylvania. Ex-staff often cite inadequate support, discipline problems and poor pay.

Well-run mentoring could halve this rate, said Mr Carroll.

Chicago and North Carolina have also embraced the idea. “It’s a growing movement,” he said, but ineffectual “buddy” programmes in which seasoned staffers informally counsel newcomers often get lumped in with more rigorous schemes.

“True mentoring involves training and well-structured time,” Mr Carroll added.

Such schemes mark a shift from recruitment drives to a new focus on keeping existing staff. Florida recently pledged to halve its teacher turnover, for instance.

“Conventional wisdom is wrong,” said Mr Carroll. “We don’t have a teacher shortage, we have horrendous teacher attrition. The problem is that our schools are like revolving doors.”

Philadelphia expects to recoup its multi-million dollar investment in a few years, said Mr Hanna. A new teacher quitting after three years can cost $50,000 (pound;28,000) in lost recruitment and training expenses, while the average outlay for a mentor is $3,000.

Philadelphia’s coaches have been relieved of their day-to-day teaching duties but are paid the same salaries.