Two schools, held up as examples by the Qualifications and Curriculum Authority (QCA) for their integrated curricula, have had to revise their radical methods following highly critical Ofsted reports.
Chafford Hundred Campus in Grays and Bishops Park College in Clacton-on- Sea, are among 16 schools highlighted on the QCA website for "promoting innovation" and "putting together an excellent curriculum".
But both Essex schools have had to rethink organising lessons by themes rather then traditional subjects after Ofsted condemned them as "inadequate" last year.
Both headteachers said that changes were needed but they remain committed to some form of integrated curriculum and that their schools are back on track.
Ofsted's verdicts raise important issues about the integrated approach, which is typified by the RSA (Royal Society for the encouragement of Arts, Manufactures and Commerce) "opening minds" model used by more than 200 schools in England.
The inspectors complimented the model, describing Chafford's curriculum - which is based on "opening minds" - as "good" and Bishops Park's curriculum as "innovative and designed with great care and imagination". But that did not mean it worked in practice. Inspectors found that some teachers in both schools lacked the skills needed to teach it.
The QCA site states that: "Chafford Hundred Campus is a secondary school that has designed a personalised curriculum around competences, and never looked back." In fact, looking back is exactly what it had to do following an Ofsted report in May 2007 that gave it notice to improve.
The QCA compliments Chafford on its "fresh approach" that "puts students' needs at the heart of its thinking". But Ofsted found the progress of key stage 3 pupils had declined over the previous three years. They joined the school with standards in line with the national average, but had not made sufficient progress.
"Not all teachers have the skills required to manage a thematic approach to the curriculum," inspectors concluded. High-ability pupils were not making enough progress.
In May 2008, inspectors rated the whole school as "good", but only after it had made changes to the KS3 curriculum to "achieve a better balance between thematic teaching across related subjects and teaching more subjects discretely".
Ofsted told the school it must continue to introduce specialist teaching in subjects because of its "legacy of past underachievement".
The full Bishops Park article is no longer available on the QCA website, possibly because the school is now in special measures. But it still proclaims the school has "a curriculum like tartan" that makes "learning engaging and fun by organising the key stage 3 curriculum around themes rather than subjects".
However, when inspectors visited in October 2007, they deemed the school "failing" and said that its curriculum did not "provide enough academic challenge or allow students to achieve as well as they can in individual subjects".
Some teachers lacked "the subject knowledge or skills they need to implement the college's thematic lessons successfully," the report said.
"There is insufficient consistent intellectual challenge for the more able students to enable them to achieve high national curriculum levels."
The thematic approach often resulted in inaccurate marking against national curriculum standards, inspectors found.
The school remains in special measures, but Ofsted has since deemed it to have made "satisfactory" progress. In July, inspectors welcomed a KS3 curriculum that was to be introduced this term. But they warned that "further work is needed to determine whether the balance of time devoted to individual subjects is appropriate".
Rita Gardner, director of the Royal Geographical Society, who drew attention to the two schools at the Commons schools committee last week, told MPs: "I do not think that, for many schools, integrated learning is a good way of organising the teaching and learning of the curriculum."
Chris Tomlinson, Chafford's headteacher, said: "We were too ambitious with the integrated curriculum. I think that is what Ofsted was saying and, to be honest, I agree with them. Now it is a fantastic advert for the school, but it has taken a while to get right."
He responded to the criticism by removing art and science from the integrated curriculum and ensuring they were taught by specialist staff.
But the themed approach had improved attendance and test results.
Nick Pavitt, who became executive head of Bishops Park after the 2007 Ofsted report, said: "The curriculum didn't work here because the leadership and management arrangements didn't ensure it worked.
"Basically, we were stuck in the 1970s. In the 1970s, there was lots of integrated humanities going on but it lacked rigour.
"What we've tried to do here is put the rigour back in."
Mr Pavitt found it was possible for Year 9 pupils to miss crucial parts of the maths curriculum under the old model. So he took maths and science out of the integrated curriculum and they are now taught by specialist teachers.
But he does not rule out returning the subjects to integrated lessons in the future.
A QCA spokesman said: "We have been using case studies for the past five years to illustrate how different schools are using the curriculum in a variety of contexts, some very challenging.
"They do not present schools as `beacons' but provide examples of how the curriculum can be organised as a starting point for discussion in other schools."
BISHOPS PARK VERDICTS
QCA: "Engages its KS3 learners by organising the curriculum around themes rather than subjects."
Ofsted: "There is insufficient consistent intellectual challenge for the more able students to enable them to achieve higher national curriculum levels . The thematic approach to teaching, and the need for teachers to teach two or more subjects, often results in a lack of accurate marking against national curriculum standards."
Head: "We were stuck in the 1970s."
QCA: "Chafford Hundred Campus breathes promise. With its uplifting design, its up-to-the-minute technology and, most importantly, its transforming approaches to teaching and learning, the campus is futurebound. Take one step over the threshold and you're almost there."
Ofsted: "Students join the school in Year 7 with standards . in line with the national average, but most do not make sufficient progress while they are at the school. Not all teachers have the skills required to manage a thematic approach to the curriculum."
Head: "We were too ambitious."