Testing seven to 11-year-olds is interfering with the teaching of science at schools across England, two independent reports said.
The reports, published by medical research charity The Wellcome Trust, said national testing has a detrimental impact on learning at Key Stage 2.
Each report looked at English primary science teaching over the past 60 years to identify trends and draw conclusions about the future.
Professor Wynne Harlen, of the University of Bristol and author of one of the reports, said monitoring how well students are responding to teaching is important, but target-setting has a negative effect.
She said: "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: "There is a considerable body of research evidence that shows children's own ideas are often in conflict with scientific ones.
"If these are taken into the secondary school they can inhibit effective learning, so science learning definitely needs to begin in primary school. The conflict leads many to find science too hard, too confusing and too remote from their real experience."
The second report was authored by Professor Peter Tymms and colleagues at the Centre for Evaluation and Monitoring at Durham University. They took a more quantitative approach to the data but reached similar conclusions, the Wellcome Trust said.
Published together, these reports are the first in a series of paired 'Perspectives' commissioned by the Wellcome Trust to stimulate debate about the best way to teach science in schools.