Primary struggle to grasp abstracts
The interim findings - three years into a five-year study being carried out by the Association of Science Education - back plans to move the study of forces to the secondary curriculum in 2000.
But overall, young children do make progress in understanding scientific concepts, such as evaporation and plant growth - with their thinking becoming markedly more sophisticated from age nine onwards.
The interim results of the survey, by the ASE's primary committee, will be reported to the association's annual meeting at Reading University next week.
The 53 pupils being tracked in the study are probably not typical, having been put forward by association members or science teachers. But if these children, coming from science-supportive home environments, are struggling then probably so too are their classmates, according to Di Wiggins, senior lecturer in primary science at the University of Central England, Birmingham.
Five and six-year-olds asked what happens to the water in a wet towel say it's "just gone". But by nine, they are able to talk about, evaporation and absorption.
Questions about the forces acting on a book on a table cause the most confusion, even in later years. Older children mention gravity, but not always in the right context. They find it easier to talk about science rooted in daily life than more abstract concepts such as forces, which are hard to "see", she added.