The National Union of Teachers - Britain's biggest classroom union - insist newly-qualified staff should only spend three days out of every five in front of pupils.
It is also calling for the working week to be slashed to 35 hours and a break for any teaching session lasting more than two hours.
The demands come amid claims teachers are being over-worked.
Christine Blower, the union's acting general secretary, claimed Government reforms introduced to cut bureaucracy and ease workload had failed.
She said teachers were working increasingly long hours - causing many to quit the profession because of stress.
But the comments were branded "crass" by parents.
Margaret Morrissey, from the support group Parents OutLoud, said: "It is absolutely crass to be raising it at this particular time. There are significant numbers of people out there who would break their arms for a secure job in teaching at the moment. I have every sympathy with teachers wanting more time to plan things, but I am not sure it is wise to be talking about it when the country is deep in recession."
Under a deal brokered between ministers and teachers in 2003, all staff are supposed to get the equivalent of a morning or afternoon a week outside the classroom to mark and prepare work.
The agreement resulted in a huge increase in the number of support staff recruited by schools to complete tasks such as photocopying, filing and putting up displays.
But an official report last year suggested teachers' hours were on the rise.
The NUT, which represents around 200,000 staff, is calling for a new contract spelling out a series of "teachers' rights".
A motion being put to the union's annual conference next month calls for teachers to have "a minimum 20 per cent non-contact time", rising to 40 per cent among staff in their first year in the job.
They should have the right to a break in "any school session that exceeds two hours" and teachers should not be "required to attend meetings of staff after school more than one evening a week". Any after school meeting should also be limited to 90 minutes.
The motion - backed by the union's ruling executive - also called for teachers in the job for at least seven years to have a term off to brush up on their skills.
The union has already demanded all classes be cut to at least 20 pupils. (By Graeme Paton, Education Editor Last Updated: 4:28PM GMT 27 Mar 2009)