ANN ARBOR— If America wants more women scientists, American girls should receive more hands-on laboratory experience in middle-school science classes.

That is one of the key findings of a University of Michigan study, to be presented April 22 at the annual meeting of the American Educational Research Association . The study, funded by the National Science Foundation and conducted by U-M researchers Valerie E. Lee and David T. Burkam, is based on data from a nationally representative sample of 18,719 8th-graders.

“Girls’ achievement in physical science is significantly lower than boys’,” reports Lee, U-M associate professor of education. ” This gender disparity is greatest among the most able students, the pool from which tomorrow’s working scientists will emerge. ”

Lee and Burkam, a U-M mathematician, analyzed the achievement scores of roughly equal numbers of boys and girls from about 1,000 American middle schools. They compared student scores on tests of physical and life sciences, and analyzed how gender differences in achievement were related to activities both inside and outside the science classroom, as reported by teachers. The researchers also analyzed how school and student characteristics were related to student achievement in science.

“The typical explanation for female underachievement in science and underrepresentation in scientific professions is that girls just don’t want to take physics,chemistry and calculus,” says Lee. ” But by focusing on how girls vs. boys are doing in science in the 8th-grade” before they have much choice of science coursework” we have documented that a female achievement disadvantage occurs before personal choice comes into play. ”

While the study findings reveal a larger gender disparity in science achievement than had been previously identified, because of its separation of the test into the two fields of science, it also identifies a potential way to correct the problem.

Although only a quarter of American 8th-graders have weekly laboratory experiences in their science classes, Lee and Burkam found that these regular lab experiences have a positive effect on female, but not male, science achievement.

“Such school activities may be especially advantageous for girls precisely because they less often engage in such activities on their own,” the researchers note. “Additionally, lab work is often conducted in pairs or small groups, and girls tend to respond more favorably to cooperative, small-group environments. ”

To increase girls’ success in science, the researchers conclude, teachers should provide more hands-on laboratory experiences, especially when students are studying the physical sciences. Lee and Burkam also recommend that teachers and parents encourage girls to participate in science clubs and fairs, and to visit science museums.

“Girls don’t take part in these activities as often as boys do,” they note. ” But it isn’t necessarily because they aren’t interested in science, as some people claim. Children and early adolescents very seldom decide all on their own to go to science, or any, museums. Rather, their parents take them and their teachers urge them to go.

“How do girls become less interested in these activities than boys do? How do girls become afraid to ask questions in science class? How do they come to think of science as less useful or interesting than boys do? Such attitudes are learned, and parents and teachers teach them. ”