There has been a dramatic drop in the proportion of pupils able to master basic maths and science concepts as they leave primary school, a comprehensive study of 10,000 11-year-olds has found.
The research, which looked at the performance of 11-year-olds in 1976 compared with Year 7 pupils from 2000 to 2003, blames recent government initiatives for a decline in understanding. It also blames teachers for narrowing their pupils' knowledge by teaching to national tests.
The study compared how pupils grasped such concepts as volume, weight, density and displacement.
Problems included comparing the same volume of liquid in a wide beaker and a narrow tube, and looking at the displacement of liquid by blocks of similar size but different weights. In 1976, 33.4 per cent of boys and 23.9 per cent of girls showed a high performance in these tests, compared with just 5.7 per cent of boys and 4.7 per cent of girls in 2003-4.
Professor Michael Shayer of King's college, London university, whose research is due to be published in the British Journal of Educational Psychology, said the decline between 1976 and 2000-1 (when 15.2 per cent of boys and 8.1 per cent of girls performed well) may be down to pupils playing more computer games and watching television rather than experimenting with tools and other objects around them.
He blames the further drop between 2001 and 2003-4 on government initiatives such as the numeracy and literacy strategies, which take up valuable time, leaving fewer opportunities for practical work and learning through play. "These figures make it difficult to believe in the validity of the year-on-year improvements reported nationally on key stage 3 Sats in science and mathematics," he said.
One test involved a brass block and a Plasticine block of the same size.
These were passed round a class and pupils were asked which would displace more liquid when put into a beaker of water. In 1976, 54 per cent of boys and 27 per cent of girls understood that volume, not weight, was the determining factor. But by 2003-4, just 17 per cent of both sexes understood this.
Dr Robert Coe of Durham university, one of the researchers, said: "The scale of this decline is quite shocking. It is rare that you get such stark evidence of standards falling like this. This test is a good measure of pupils' fundamental understanding of the building blocks of science."
Professor Peter Tymms of Durham university, who has monitored the progress of 4,000 primary schools worldwide, said the findings could explain a recent drop in pupils studying sciences at GCSE.
He called for an independent body to be set up to continue monitoring understanding as pupils enter secondary school.
He said: "These tests get at the fundamental cognitive development levels and our understanding of the physical world and all that it entails. This is something that we should sit up and take notice of, and it makes me worry about the impact of league tables, Ofsted, and teaching to the test."
Primary heads admitted government intiatives had had an impact on timetables but said pupils were still achieving a sound understanding in maths and science.
Diane Woodward, head of Parson Cross primary in Sheffield, said: "I would accept that the changing lifestyles of children is possibly having an impact on achievement. The drive to raise standards has had an impact on schools. The curriculum has been crowded, and we probably did not spend sufficient time on allowing children enough time for practical work - but increasingly, schools are focusing on how children learn through formative assessment and teaching them how to learn."