How much freedom should teachers have over what they teach? Should pupils be guaranteed a broad education or should only basics such as literacy and numeracy be compulsory?
These arguments and others started before the national curriculum was launched 20 years ago, and show no sign of abating. Indeed, fuel has been added to these controversies by major changes coming in September. The TES will be examining those changes and how they will affect schools.
But there is one thing that few people now argue about: whether there should be a national curriculum at all. Among the dozens of submissions to this year's parliamentary inquiry into it, only the Independent Schools Council raised the question as to whether a national curriculum is necessary.
In 1988, it was all very different. The idea of a nationally prescribed set of subjects to be taught had been intensely contentious since the 1930s. It had been commonly held that for a government to lay down centrally what should be taught bore overtones of fascism.
Indeed, Ronald Gould, general secretary of the National Union of Teachers from the mid-1940s to 1970, said: "I have heard it said that the existence in this country of 146 strong, vigorous local education authorities safeguards democracy and lessens the risk of dictatorship. An even greater safeguard is the existence of 250,000 teachers who are free to decide what should be taught and how it should be taught."
The NUT was still opposed to a central curriculum in 1986 when Kenneth Baker proposed it after being appointed education secretary. The union was one of 5,000 organisations and individuals to express an opinion during consultation on its introduction.
But the union, in its 2008 evidence to the Commons inquiry, said its view had now changed. Today the NUT argues: "A national curriculum which is part of an effective education system and which focuses on achieving equality of opportunity for all children and young people has a positive, indirect influence on standards."
Though the concept seems accepted, submissions to the committee illustrate how much else is contested. Foremost is the debate about what should be taught. Ever greater number of lobby groups are calling for their subject to be given space.
Financial literacy and citizenship have been among recent additions to the original 10 subjects, with others, including PSHE (personal, social and health education) waiting in the wings.
But is it possible to stipulate huge swathes of content without overloading teachers and pupils? This was an especially acute dilemma between 1988 and 1993, when subject groups came up with recommendations on what should be taught. Added together, they far exceeded the time available.
Changes to the secondary curriculum this year aim to pare back prescribed content and reduce duplication between subjects. But disagreements are continuing, with subject associations this time warning that their teaching is under threat in the face of more cross-curricular project work.
Mick Waters, head of curriculum at the Qualifications and Curriculum Authority and the man who spearheaded the secondary curriculum changes, described it as a "national treasure" over which professionals should feel more ownership.
These views have helped make him popular with many teachers and heads. But he is deeply unpopular with others for stripping back the content of some subjects.
Some concerns that surrounded the curriculum when it started remain today. These include the conflict between teaching core skills and providing balance. Another is the side effects of testing.
However, one concern that is more evident now than in the 1980s is the pace of change. Monitoring reports for the QCA, based on questionnaires completed by hundreds of teachers, show many worry about the seemingly unceasing nature of reform.
An unnamed primary head told the authority's survey in 2005: "The whole educational system is jam-packed, moving so quickly (that it) doesn't allow the time or space to deliver or develop what will really inspire our pupils."
The pendulum now seems to be swinging away from subject teaching towards cross-curricular lessons. Topic-based work is more evident in primary and secondary schools. Even the new 14 to 19 diploma courses, starting in September, can blend maths and languages with their main topic.
But if the Conservatives regain power, the pendulum may swing back. Barbara Hibbert, head of history at Harrogate Grammar in North Yorkshire, said she expected they would put the emphasis back on subject teaching.
It is clear now that the pace of change means teachers will have little breathing space.
Barry Sheerman, chairman of the children, schools and families select committee, asked Jim Knight, the schools minister, this month whether the full extent of planned reforms was sensible.
"You are fiddling around with the early years, you have a review into primary, you have already made up your mind about the later years of the curriculum, and the whole diploma thing is coming," Mr Sheerman said. "Is there any chance of stability in the curriculum in the foreseeable future?"
Mr Knight agreed with him that "stability is a relative concept". Part 1 continues overleaf
Parts 2 to 5 will examine curriculum changes for different age groups, starting next week with the early years.