Edinburgh City Council said it was considering the plan, and increasing the use of non-professionals alongside teachers in the classroom, to help drive up attainment.
“In many senses you’re probably looking at a minimum of five years for a headteacher to make a proper, sustainable impact,” said Ken Cunningham of SLS. “And that will be along with the leadership team because it’s all about collegiate working.
“Some headteachers may want to have a change of career and that may involve going to another school or into a government agency or whatever, but that should be on a voluntary basis.
“More opportunities of that kind would be a good thing but to make it compulsory is not just unworkable, it’s laughable,” he told SecEd.
A report titled Vision for Schools in Edinburgh, which outlines the local authority’s goals for the next five years, has gone before councillors on the education committee.
The report will go out to consultation with parents and teachers before a final draft is published in January. It states: “Staff are our most important resource, and investment in their development is key.
“We want to strengthen support for development of staff including rotation of headteachers so they serve no longer than five to seven years in a particular school.”
Earlier this month it emerged that Edinburgh has one of the worst records in Scotland for poor children getting into top universities.
The report also proposes the use of “para-professionals”, working alongside teachers to help bring a wider range of skills and talents into schools. Teachers criticised the idea when it appeared in a Scottish government review of teacher employment last year.
Councillor Paul Godzik, Edinburgh’s education leader, said: “We want to make sure we deliver an innovative and forward-thinking approach which gives all our young people the opportunities they need to succeed.”
However, Mr Cunningham said the different nature of each school and its own stage of development were among the factors that made any cut-off point for a headteacher’s tenure too arbitrary, even if it was seven years rather than five.
Larry Flanagan, general secretary of the EIS union, also said he opposed a compulsory move.