School science "should foster a sense of curiosity"
Primary school children's understanding of science is harmed by the way England's testing system holds schools and teachers to account, reports say.
Two reports for The Wellcome Trust charity said the "high stakes" nature of tests led to the drilling of pupils rather than teaching for understanding.
The researchers said tests had a negative impact and called for a new approach to science teaching.
The government said there was no evidence testing had a negative impact.
One of the reports, by Durham University's Peter Tymms - a long-standing sceptic about claims of rising standards - said many argued that school league tables based on national test results were harmful to education.
"The results are therefore 'high stakes' and pressurise primary teachers to teach to the test rather than encourage them to teach for conceptual understanding, even if the tests themselves are designed to encourage clear thinking," he said.
"Despite the pass rates in public examinations later in secondary school, research suggests few students acquire a proper understanding of the science curriculum."
Instead, the purpose of primary school science should be to "foster a sense of curiosity and positive attitudes in the young child".
Fellow researcher Professor Wynne Harlen said in a separate report: "Research shows unequivocally that testing in science has had a detrimental impact on learning and teaching, particularly in the years when the tests take place.
"Of course it is important to know what children have achieved, to report this to parents and other teachers and to keep records that enable proper evaluation.
"The negative impact derives not from the assessment process as such, but as a consequence of the policy of using results to set targets and to judge teachers and schools solely on the basis of test results," she added.
Instead tests should be replaced by moderated teachers' assessment, so that progress in the full range of skills can be recorded and reported, said Prof Harlen.
She also called for primary pupils' learning in science to be evaluated against a wide range of indicators of which pupils' achievement would be only one.
A spokesman for England's Department for Children, Schools and Families said there was no evidence in either report that tests were damaging.
"Science is a priority in schools at all levels," he said.
"We are working to improve the teaching and learning of science in schools and to inspire more young people, from all backgrounds, to study and work in science.
"Good teachers know that the best way to keep pupils engaged is to give them a broad, in-depth understanding of a subject - we want science lessons in schools to be exciting and inspiring with more science in action in the classroom to enthuse budding scientists."