Allowing teachers to spend 10% of their working week on planning, preparation and assessment should enable them to plan lessons better and be more focused on the needs of every child, the government says.
Janet Coaley is 'loving' the new working arrangements
The changes - so-called PPA time - were introduced at schools in England this term and amount to a major shift in working practice.
They came in despite complaints from many quarters.
Some teaching unions had warned the financial burden would be too much for some schools, and that without proper funding, the agreement would be unsustainable.
The National Union of Teachers refused to sign up to the deal, saying it feared schools would use non-qualified staff to take classes.
But Janet Coaley is a happier and more focused teacher this term. Because of the way her school has implemented PPA she is able to teach her specialist subject - PE - more often, plan next week's lessons and focus on students' needs.
"It's nice that someone has said they understand that teaching is not just a 9am to 3.30pm job with long holidays," she said.
This recognition could help recruit other teachers into the profession, she says.
"Where I am covering another teacher's PPA time, I think the children see it as a treat. And they all know me and are comfortable with me."
The head teacher at Colebourne Primary School in Birmingham, where Janet teaches, has reduced the number of teachers pupils are taught by as a result of the reforms.
Vicki Herrick, who led a corsortium of Birmingham primary schools looking at how to best implement the deal, now only uses one regular supply teacher, whom the pupils know well.
Two other teachers in her staff cover other teachers' PPA time. But they also carry out the assessment and lesson planning for those classes - so their role is not just limited to "covering" the period when their teacher is away from the classroom.
Vicki Herrick stressed this was not an isolated agreement, but part of a "re-modelling" process for Birmingham's schools which began in summer 2003.
That whole process - which included releasing teachers from 24 administrative tasks and covering for absent colleagues - was about ensuring teachers could concentrate on a smaller range of functions, making schools more efficient, and ultimately raising standards, Mrs Herrick said.
PPA would not be the end of that process.
"It is there to allow teachers to focus even more on pupils' outcomes," she said. "That something extra will arise naturally out of teachers' professionalism, because they obviously want to focus on the needs of every child," she went on.
Vicki Herrick says time to plan for PPA has been very valuable
Mrs Herrick is testing two solutions this year: Allowing Janet Coaley to teach six sessions of her specialist subject, using one supply teacher to cover three sessions, and organising a job share system in two year groups.
While the teachers who are job sharing are not with their own class, they cover other teachers' time away from their pupils.
The solutions will not be the same for every school, she said, and she will monitor the effect on standards and teachers of her new arrangements.
But teachers appear to be fresher during the school day thus far, she said.
Mrs Herrick said she could understand how lack of money could lead some schools to make greater use of classroom assistants.
"This represents a considerable extra expense," she added.
"I have 14 classes so it amounts to seven days' cover a week."
Schools with falling rolls would be most vulnerable over the longer term, as a new three-year budget to be announced in November will be calculated per pupil, she said.
So is there no basis for the scare stories of unqualified staff teaching classes?
"My impression is that the government originally thought it wasn't always necessary to have a teacher in front of the class," Mrs Herrick said.
But the local PPA agreement for Birmingham's schools precludes the use of classroom assistants to cover those sessions.
Level of knowledge
However, not everybody is reaping the benefits of reform.
The government says schools' funding settlements for 2005/6 meet the costs of the changes, and include a minimum funding guarantee of 5% for primary schools.
But Avril Chambers, negotiating officer with the GMB union, said head teachers had to be satisfied that staff covering planning time had the necessary skills.
There needed to be a firm distinction drawn between cover supervision - covering for short periods when a teacher is out of the classroom - and covering a whole lesson which a teacher is timetabled to teach.
The school says it has relied on support from the local authority
"Classroom assistants with that level of knowledge would be level 4 - but we know some schools are using those on level 3."
One classroom assistant in a special needs school told the BBC News website that although a level two teaching assistant, she was taking whole classes of special needs pupils on her own on a regular basis.
Her school told her it did not have the money to increase her salary to level three, she said.
Avril Chambers said some teaching assistants were being paid at a higher rate on an ad hoc basis, just where they covered a teacher on planning time, which she said was unacceptable.
"You wouldn't reduce teachers to an administrative rate of pay when they are out of the classroom, would you?"