Key stages could be abolished in the Government's review of the national curriculum and replaced with year-by-year outlines of the knowledge pupils should acquire.
The TES has learnt that members of the expert panel leading the review believe there are "serious issues" about the multi-year key stage structure the national curriculum has had since its 1988 introduction.
They note that "most" high-performing nations have a curriculum outlined year by year and believe the language of key stages and the linked "levels" of attainment can be difficult for parents to understand.
Panel chair Tim Oates told The TES: "If parents are clear about what it is that is actually being covered every year they will be better placed to support their child at home.
"There are serious questions in relation to the levels and key stages in the form in which they are currently stated in the national curriculum."
He also said using a "level" to describe a pupils' attainment was insufficiently precise.
"It is not enough to know whether a child is level four," said Mr Oates, a Cambridge Assessment research director.
"Parents want to know whether their child is struggling with a particular area of the curriculum. Or, conversely, areas in which their child has particular strength."
Panel members think a year-by-year approach could be particularly suitable for subjects such as maths or physics where one area of knowledge builds on another and it is important to learn topics in a logical order.
But they accept it might be less appropriate for a subject such as English, where a more flexible structure could be helpful.
No decisions have been taken yet but the review's remit would allow a mixed approach, with the structure of the curriculum changed in some subjects and not others.
It says the review will advise on: "The extent to which the content of the national curriculum should be set out on a year-by-year basis in order to ensure that knowledge is built systematically and consistently."
Early results from the review's consultation have shown a mixed response to the idea, with some wanting to stick to a structure they have become used to.
A year-by-year structure could also be seen by some as increasing the level of prescription in the curriculum.
But it would not prevent the review delivering more freedom for schools by slimming down national curriculum content so there is more space and time outside it.
Russell Hobby, general secretary of heads' union the NAHT, said: "If we are talking about a curriculum where the overall level of prescription is slimmed down, then having the content more closely aligned to age might not be a bad thing."
CURRICULUM REVIEW - On the timetable
- January 2011 - phase one is deciding the future status of the eight non-core subjects, the support needed by schools, and developing programmes of study in English, maths, science and PE.
- Autumn 2011 - ministers consider recommendations on the above.
- Early 2012 - public consultation on draft programmes of study for core subjects in time for teaching from September 2013.
- Phase two - programmes for other subjects passed to ministers by autumn 2012, with public consultation in early 2013 and teaching from September 2014.