In science, U.S. fourth graders placed eighth, and eighth graders ranked 11th. Those rankings have dropped - the United States was sixth in fourth-grade science and ninth in eighth-grade science in 2003.
The mixed results drew disappointment from many quarters.
"Americans have never thought of ourselves as part of the mediocre middle, and now is hardly the time to get comfortable with that status," Kati Haycock, president of the Washington-based Education Trust, said in a statement.
F. Joseph Merlino, project director of the Math Science Partnership of Greater Philadelphia, said parents ought to be concerned.
"We are not in the 1960s any longer, when the U.S. was preeminent," Merlino said. "They should be saying, 'What about my children? Are they going to be able to get a job and compete and make their way in the world?' "
Worldwide, a representative sample of 425,000 students took the TIMSS. While some critics say the test isn't a fair comparison, given the economic diversity and decentralized education structure of the United States, it is clear that although American students do about as well as students in other developed nations, some Asian countries continue to dominate.
Six percent of American students scored at the highest level in math. In the three top-performing countries - Taiwan, South Korea and Singapore - more than half of the students reached the top tier.
But Americans scored in line with other developed countries, said Ina V.S. Mullis, a Boston College research professor and co-director of the study.
