Researchers have found one more clue in their search for the reason that girls don't do as well as boys in math: a nation's culture.
Scientists compared math and reading scores on tests given to thousands of 15-year-old students in 40 countries and then examined how each country ranked in terms of gender equality.
While girls generally scored lower in math than boys, girls did better in countries with greater gender equality than in less progressive countries.
Girls performed best in countries such as Norway and Iceland, which have progressive gender policies, and worst in countries such as Turkey, which scored relatively low on standard measures of gender equality. The U.S. fell somewhere in the middle, the researchers say.
Girls scored higher in reading everywhere - and their reading advantage widened in countries with more gender equality, according to the report in today's edition of the journal Science. But only in Iceland, a country known for its homogeneous population, did girls score better than boys in both reading and math.
Experts said that without more studies, they could not explain why girls' performance there was so far ahead of their counterparts in other countries. "All I can say is, don't mess with the girls from Iceland," said Luigi Zingales, a finance professor at the University of Chicago who is a co-author of the report.
There has been a variety of theories to explain the gender gap over the years - some biological and some psychological.
"We really don't know," Zingales said.
The researchers used 2003 results from the Program for International Student Assessment, which tested 276,000 children representing a cross section of each participating country's overall population. Math skills tested included basic geometry, algebra, arithmetic and probabilities.
Gender equality profiles were determined by measures such as the World Economic Forum's gender gap index, which ranks countries based on economic and political opportunities for women, and on other barometers such as longevity rates. The U.S. ranked 23rd of 128 countries in the WEF's 2006 analysis.
Girls in the U.S. scored an average 10 points lower than boys in math, which was about the international average.
Maryland educators say the study highlights the importance of cultural attitudes in the choices students make when deciding on high school courses and career tracks.
