The proposals by the Convention of Scottish Local Authorities (Cosla) include creating a link between teaching standards and pay, barring more teachers from the profession for being poor educators, and introducing short-term contracts subject to appraisal for promoted posts.
The report could end the 35-hour week established in the 2001 Teachers' Agreement known as the McCrone deal.
The report, commissioned by the Scottish Government, was based on feedback from councils which said budget cuts and the new school system, Curriculum for Excellence introduced this year, meant changes were necessary.
However, unions criticised the suggestions, describing the proposals as "madness". Ronnie Smith, general secretary of the EIS, described the submission as "a stream of consciousness - some of it quite off the wall".
He added: "If they try to do things like extend teachers' working year, they're going to hit a brick wall. They have some of the longest working hours in Europe and they've been hit by issues such as a two-year pay freeze and a 50 per cent increase in pension contributions."
He said the call for flexible working seemed to mean "work all the hours God sends, at the hours we want you to".
Ann Ballinger, general secretary of the Scottish Secondary Teachers' Association (SSTA), said: "Clearly, the people who wrote this know a bit about education, but large parts of it are complete nonsense and will make teachers very angry.
"I have never had confidence in the assurances we've been given by negotiators, but this just proves my lack of confidence in their integrity was justified."
Cosla says the landmark McCrone deal, which gave teachers a pay rise of 23 per cent over three years, led to peaceful industrial relations, but a "less clear-cut" impact on children's achievement and attainment.
Inservice days, under the suggestions, could increase from the current five a year, but could take place during pupil holidays rather than term time which, Cosla says, is too disruptive to pupils.
And it suggested "counting hours" was inappropriate for professionals, proposing a more flexible model of about 140 hours a month. Cosla said the government-commissioned review of the McCrone deal, being carried out by Stirling University principal Professor Gerry McCormac, should be viewed as an opportunity to be as radical in 2011 as McCrone was in 2001.
A Scottish Government spokesman said: "Much has changed since the current agreement on teacher employment was introduced ten years ago."
A Cosla spokesman said: "Change is needed, but we are not wedded to any particular single approach. Our submission … is intended to point up areas for debate where it should be possible to look at options for new ways of working. It would be wrong to concentrate on any one thing in isolation, or to assume these are final proposals."