that whereas primaries are "continuing to forge ahead", improvements in secondaries have "stalled" over the past 12 months. Their failure to stretch the most able students is characterised by a "worrying lack of scholarship permeating the culture of too many schools", chief inspector Sir Michael Wilshaw writes.
In particular, Ofsted criticises school sixth forms for "failing to set aspirational standards for their young people".
Since the coalition government came to power, schools have been encouraged to open sixth forms and compete with existing post-16 providers. Since 2010, 169 new sixth forms have opened; across England, almost 1,200 schools now run a sixth form attended by fewer than 100 students.
"Where school sixth forms are very small, they frequently offer too narrow a range of subjects or teach those subjects poorly," Ofsted's report says. "The quality of teaching is variable and senior staff do not monitor this teaching effectively. In some cases, the success or failure of a course depends solely on one individual member of staff."
Students attending small school sixth forms "achieve considerably poorer results than those in larger sixth forms", the inspectorate claims.
"We are concerned that small and ineffective sixth forms often guide young people on to the wrong courses because of the limited range available.Often, young people end up abandoning an academic course they should not have started in the first place and leave sixth form with no additional qualifications."
The findings were welcomed by James Kewin, deputy chief executive of the Sixth Form Colleges' Association. "Ofsted are saying that small school sixth forms are not effective, yet the current policy drift is to increase their number," he said. "It doesn't make any sense. Ofsted has added to the doubts that this policy works."
Although a higher proportion of secondaries were rated outstanding than primaries, the report argues that greater improvement was evident in the primary sector. In many cases, even high-performing primary pupils' attainment levels dropped when they moved to secondary schools, and inspectors identified issues with the teaching of the most able children in about a third of the secondaries inspected this year.
But Ofsted's analysis has come in for some criticism. Sam Freedman, who was an adviser to former education secretary Michael Gove and is now director of research, evaluation and impact at Teach First, argued that the "certainty and confidence" of the inspectorate's claims were "simply not justified by the available evidence".
"The trends in the data are small, complex and contradictory. They do not show that suddenly primaries are great and secondaries are stalling," he added.
The claim was also disputed by Brian Lightman, general secretary of the Association of School and College Leaders.
"Ofsted has failed to recognise that overall attainment by 16-year-olds is effectively capped by the current GCSE awarding process," he said. "As student attainment is the critical element in the Ofsted grading, it is no surprise that the proportion of schools graded good or better is relatively unchanged."
The annual report also warns of the "pressing" issue of falling numbers of trainee teachers. And although it praises "the best multi-academy trusts" such as the Harris Federation and Outwood Grange Academies Trust, it says that the decline of many "isolated" stand-alone academies is "disturbing". Of the 89 converted academies whose rating fell to inadequate or requires improvement, 66 did not belong to a chain.
Simon Burgess, professor of economics at the University of Bristol, said Ofsted's risk-based approach to selecting which schools to inspect made it difficult to assess overall trends. "To a degree they reflect real changes in schools, and to a degree they may reflect changes in which schools were chosen for inspection," he added.
In response to Ofsted's report, education secretary Nicky Morgan maintained her conciliatory tone towards the profession, while acknowledging that there was "more [for schools] to do". She added that the sector "should be incredibly proud of the progress that has been made in the past few years".
Ofsted's key points
- Primary schools are "on an impressive upward trajectory", with more than eight in 10 rated good or better.
- Progress in secondaries has "stalled", with more in special measures than last year.
- In 13 local authority areas, children have less than a 50 per cent chance of attending a good secondary.
- Problems with teaching the brightest pupils were found in about a third of secondary inspections.
- Leadership and management is good or outstanding in 84 per cent of primaries and 77 per cent of secondaries.
- Teaching is good or outstanding in 82 per cent of primaries and 72 per cent of secondaries.