Maths and science teaching in many colleges is "uninspiring" and lagging behind other subjects, inspectors have warned.
Ofsted's annual report, published this week, highlights the disparity between the quality of teaching and learning in different subject areas, and claims that too many colleges are no better than satisfactory, with limited scope for improvement.
Six colleges were rated outstanding in 200910 - just a third of the 18 that got top grades previously. Thirty-eight were classed as good, 31 as satisfactory and four as inadequate.
Of the 79 colleges inspected, 17 saw their gradings drop, while 16 saw an improvement.
Lorna Fitzjohn, Ofsted's divisional manager for learning and skills, put the apparent drop in standards down to the new inspection framework under which colleges with weaker ratings are inspected more regularly.
But she told The TES there was a gulf between standards of teaching in different subject areas. Engineering and manufacturing technologies, as well as arts, media and publishing were singled out for particular praise.
However, she said teaching in science and maths was "often dull and uninspiring", adding: "Teachers don't always check learners understand sufficiently what they have been taught."
The report says: "This is a concern because of the particular importance for this sector subject area for economic competitiveness.
"Enrichment opportunities are too limited, courses at foundation and intermediate levels are not well developed and progression routes to advanced learning are unclear," it adds.
Describing inspectors' findings at struggling colleges, the report says: "There is insufficient focus on the effectiveness of teaching and its impact on learning ... Low expectations, insufficient challenge, particularly for the most academically able, and the lack of clear learning objectives all impede the progress made by learners."
In contrast, the report praised colleges serving a high proportion of disadvantaged learners, with 44 out of the 62 inspected classed as good or outstanding; and work-based learning providers, with 48 per cent being rated good or better - up from 42 per cent in 200809.
The report also found that too many satisfactory colleges failed to improve on previous inspections. "Some of them we go back to, and they haven't done anything about these things," Ms Fitzjohn said.
Lynne Sedgmore, executive director of the 157 Group of FE colleges, said: "We're disappointed by the findings. The context of inspections keeps getting harder, but we believe the colleges are constantly raising their game. It falls to the outstanding and good-rated colleges to help the satisfactory and inadequate ones to help raise standards."
The report found that gradings for sixth-form colleges had also dropped, with half of those inspected judged good or better, compared to 78 per cent last year. Two were classed as inadequate.
Work-based training, contracted by the Department for Work and Pensions, was "the weakest area of post-16 provision", with 28 out of 34 providing "inadequate outcomes".
"We have some young people who have not achieved jobs since coming out of it, and that is the aim of the programme," Ms Fitzjohn said.
DISADVANTAGED PERFORMING WELL
- 48 per cent of the providers inspected by Ofsted were good or better - up from 42 per cent in 200809.
- Too many colleges are no better than satisfactory, with limited capacity for improvement.
- Colleges serving the most disadvantaged learners perform almost as well as those with high levels of advantaged students.
- Science and maths teaching are classed as weakest subject areas.
- Learning and skills provision contracted by the Department for Work and Pensions performed the worst, with 28 of the 34 providers rated inadequate.