The NASUWT and other teachers' unions confirmed this week that they are working with the Department for Education and Skills to assess the workload implications of all the Government's planned school strategies, such as the 14-19 agenda.
The Trades Union Congress has called today "Work Your Proper Hours Day", encouraging people to leave work at 5pm.
It suggests bosses take their hard-working staff out for a beer tonight.
And it has set up a website so employees can bombard bosses with anonymous emails, reminding them of their unpaid work.
If teachers did all their unpaid hours at the beginning of the year they would not get paid until March 24. For the average worker the date would be February 23.
At some academies and independent schools, such as Eltham college in south London, teachers receive a top-up to recognise the extra work they are expected to do. Danny Cooper, the college bursar, said teachers there receive an "Eltham supplement" of more than pound;4,000 a year. "It is in recognition that they do go the extra mile, with the time they put into sports and arts and other extra-curricular activities," he said.
Brendan Barber, TUC general secretary, said there were some real, but slow, signs of progress in education over the last five years as working hours dropped. "But we need to speed this up," he said. "Regular excess unpaid overtime is a recipe for burn-out and inefficiency. Of course we are not calling for Britain to become a nation of clock-watchers. Most staff are happy to put in some extra time when there's an emergency or extra pressure of work, but it should not be taken for granted week in, week out."
The pay agreement for teachers in the state sector does not provide for any overtime - but it is generally expected they will do extra hours coaching sports teams and directing drama productions. Mary Bousted, general secretary of the Association of Teachers and Lecturers said:J "Guaranteed PPA time has made a difference - cutting an average of two hours a week - in teachers' working time, especially among those in primary schools, but more still needs to be done to ensure all teachers have a reasonable worklife balance."
Chris Keates, NASUWT general secretary, said the falling teachers' hours showed a trend in the right direction, but were not enough.
"The downward pressure on working hours has not been as marked as we would like it to be," she said. "I don't think teachers want to be paid for overtime. What they want is to have a job that has got manageable demands, so they can balance work with their life outside."
UNPAID WEEKLY OVERTIME HOURS
Teachers and lecturers 11.1
Fire and police officers 10.3
Corporate managers 9.5
Doctors and nurses 7.3
Civil servants 5.6
Retail workers 3.6
Customer service officers 3.1