Huge numbers of Scotland's youngsters have a poor understanding of science, a report suggested today.

Just 6% of children in primary seven are achieving expected levels of science knowledge and understanding, it said.

For youngsters in their second year of secondary school the proportion is just 17%.

Other age groups fare better, and all age groups are stronger on "science literacy" - an understanding of the impact of science on everyday life - than on science knowledge and understanding.

Cabinet secretary Fiona Hyslop said: "The survey results highlight the challenge this government has inherited - to build up capability for science teaching, to ensure that pupils can enjoy a rounded science learning experience, and that our young people understand the importance of science in the 21st century.

"We are determined to work with schools and local authorities to ensure that the previous lack of progress in science achievement in our schools between 2003 and 2007 is addressed."

Tories said the findings were of "considerable concern" but sounded a sceptical note.

Tory education spokeswoman Liz Smith questioned the definition of "science literacy".

"I'm sure I will not be alone in finding it very odd that the report claims 55% of all primary three pupils are meeting the expected targets on a very sophisticated measure of science literacy yet this falls to only 7% by primary seven," said Ms Smith.

"What on earth happens in that timescale to reduce science literacy by such a substantial amount.

"Or could it be that using the same measurement criteria in both primary three and primary seven is misleading?"

The findings were published in the third annual Scottish Survey of Achievement, a three-month "snapshot" survey conducted last spring which covered 40,000 children in 1,100 schools.

The report found that in primary three, almost 55% of pupils were "well established" in science knowledge and understanding.

This fell to fewer than half in primary five, 6% in primary seven, and 15% in S2.

"The findings suggest a significant number of pupils are not achieving expected levels, particularly in P7 and S2", said the report.

And there had been no improvement in knowledge and understanding between 2003 and 2007, the report found.

Science literacy was a measure used for the first time in the survey.

This involved testing youngsters on their ability to understand the impact of science on everyday life, take "informed" personal decisions, and read and understand the essential points of media report on matters involving science, and to reflect critically on that information.

On this measure, all age groups performed more strongly than in science knowledge and understanding.