Science teaching in primary schools has deteriorated over the last three years due to teachers' "lack of confidence", Ofsted has warned.
The new report, on the quality of science education, found that, while standards improved in secondary schools between 2008 and 2010, primary pupils' attainment remained "broadly similar" but with a "slight decline" in those achieving higher grades in exams at the end of key stages 1 and 2.
The lack of improvement is blamed on primary teachers' limited knowledge of science, the low take-up of continuing professional development and reduced levels of local authority support.
At post-16 level, five of the 31 colleges inspected were rated inadequate for science teaching - more than for any other subject.
In primaries, the proportion of pupils attaining level 3 or above at the end of KS1 dropped from 22 per cent in 2008 to 21 per cent last year.
The numbers obtaining level 5 or above at KS2 also fell in the same period, from 38 per cent to 37 per cent.
In weaker primaries, pupils had "fewer opportunities to plan and carry out investigative activities", and many repeated their learning when they moved between key stages due to "weak communication and poor continuity".
The report added that the abolition of science testing at KS2 had allowed more "varied", "engaging" and "enjoyable" lessons.
At KS3, 48 per cent of students reached level 6 last year, up 5 per cent from 2008.
Libby Steele, head of education at the Royal Society, a fellowship of eminent scientists, blamed primary teachers' nervousness on their lack of specialist knowledge.
She welcomed the "positive" findings on secondary teaching, but warned that setting "whole cohorts" of students on the same qualification hindered their individual learning and left them with "restricted" options after their GCSEs.
Annette Smith, chief executive of the Association for Science Education, said the science programme for continuing professional development "doesn't seem to be taken up so much".
"The structures are in place; we know what underpins good science teaching. Now we need to make sure that happens in every school," she added.