Thousands of secondary teachers are having to teach outside their own subjects as a radical new approach to the curriculum spreads through the country.
The Opening Minds framework encourages themed lessons that cut across traditional subject boundaries requiring staff to teach in more than one area.
A survey released to The TES this week reveals that of the 204 schools currently using the approach, 171 of them said it involved subject teachers working outside their own specialism.
The Royal Society for the Encouragement of Arts, Manufactures and Commerce (RSA) which devised the framework and conducted the survey says schools can introduce the change successfully so long as they take time to prepare.
But an assessment expert is warning that more training could be needed, because if teachers are to properly engage pupils they need to be immersed in their subjects and confident in their content.
RSA research shows that 93 per cent of comments made about Opening Minds in school Ofsted reports have been positive.
Furthermore 74 per cent of schools using the framework, for which data was available, had had their curriculum rated by Ofsted as either "good" or "outstanding", compared with 67 per cent nationally.
But at least one of these schools was still given notice to improve by inspectors who concluded that some of its teachers lacked the skills needed for a themed curriculum.
Tim Oates, Cambridge Assessment, assessment research director, said: "Research tells us that a high level of subject knowledge is essential to learning that is motivating and oriented towards deep learning.
"To realise the value of the RSA approach, resources need to be directed towards appropriate professional development."
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Bard to worse
School leaders are cancelling Shakespeare classes for teachers and pupils in the wake of the demise of the key stage 3 tests, MPs have been told.
The revelation came from the Royal Shakespeare Company this week, which said that the number of KS3 teachers booked on to its training courses had fallen by more than half.
In addition, the company is reporting a 30 per cent drop in the "outreach" work it does for KS3 teaching in schools. In a letter to members of the schools select committee, the company quotes a teacher as saying: "My senior manager will no longer release me to attend the training day as Shakespeare isn't a priority anymore."
Barry Sheerman, the committee chair, said: "It's quite chilling if schools don't want students to go and see Shakespeare if it's not examined."