The U.S. 4th-graders' 2007 science score was higher than scores in 25 countries and lower than in 4 countries. The U.S. 8th-graders' science score was higher than scores in 35 countries and lower than in 9 countries. U.S. students' 2007 science scores did not measurably differ from 1995 scores.

The Trends in International Mathematics and Science Study (TIMSS), conducted in 2007, assessed students' science performance at grade 4 in 36 countries and at grade 8 in 48 countries. The assessment is curriculum based and measures what students have learned against the subject matter that is expected to be taught in participating countries by the end of grades 4 and 8.

In 2007, U.S. 4th- and 8th-grade students scored above the TIMSS science scale average. U.S. 4th-graders scored higher, on average, than their peers in 25 of the 35 other countries that participated at grade 4 and lower than those in 4 of the other countries. Average scores in the remaining 6 countries were not measurably different from the U.S. average. The four countries with higher average scores than the United States were Singapore, Chinese Taipei, Hong Kong Special Administrative Region (SAR), and Japan. U.S. students scored higher than the TIMSS scale average on all three science content domains measured at grade 4: life science, physical science, and Earth science (see table A-16-1).

The average U.S. 8th-grade science score was higher than the scores of students in 35 of the 47 other countries that participated at grade 8 in 2007, lower than the scores of students in 9 of the other countries, and not measurably different from the scores of students in the remaining 3 countries. The nine countries with higher average scores than the United States were Singapore, Chinese Taipei, Japan, Republic of Korea, England, Hungary, the Czech Republic, Slovenia, and the Russian Federation. On the four science content domains measured at grade 8,

U.S. students scored above the TIMSS scale average in biology, chemistry, and Earth science, but their scores were not measurably different from the average in physics (see table A-16-2).

Examination of the science performance of each participating country's higher and lower performing students shows that, in 2007, the score defining the highest performing U.S. 4th-graders (those performing at or above the 90th percentile) was higher than the 90th percentile scores for 4th-graders in 27 countries and lower than the scores in 2 countries (table A-16-1). The score defining the lowest performing U.S. 4th-graders in science (those performing at or below the 10th percentile) was higher than the 10th percentile scores for 4th-graders in 17 countries and lower than the scores in 7 countries.

In 2007, the U.S. 8th-grade science score at the 90th percentile was higher than the corresponding scores in 34 countries and lower than the scores in 6 countries (see table A-16-2). At the other end of the scale, the U.S. 8th-grade science score at the 10th percentile was higher than the scores in 34 countries and lower than the scores in 8 countries.

The United States was 1 of 16 countries at grade 4 and 1 of 19 at grade 8 that participated in both the first TIMSS science assessment in 1995 and the most recent one in 2007. The average science scores in 2007 for both U.S. 4th- and 8th-grade students were not measurably different from those in 1995 (see tables A-16-3 and A-16-4).

Among U.S. 4th-graders, the science score at the 90th percentile was lower in 2007 than in 1995 (see table A-16-5). Though the U.S. 4th-grade 10th percentile science score appears to have improved, there was no measurable change in the score between 1995 and 2007 or between 2003 and 2007. The U.S. 8th-grade 90th percentile science scores in 1995 and 2007 showed no measurable differences, nor did the scores in 2003 and 2007. In 2007, the 90th percentile score was lower than in 1999. The U.S. 8th-grade 10th percentile score was higher in 2007 than in both 1995 and 1999.

Technical Notes

The TIMSS scale average was established with a mean of 500 and a standard deviation of 100, based on the average of all the countries that participated in 1995. Successive assessments have scaled the achievement data so that scores are equivalent from assessment to assessment. That is, a score of 500 in grade 8 science in 2007 is equivalent to a score of 500 in grade 8 science in 2003, 1999, and 1995. The total number of countries reported here differs from the total number reported in the TIMSS reports. In addition to the 36 countries at grade 4 and 48 countries at grade 8, eight other educational jurisdictions, or "benchmarking" entities, participated: the states of Massachusetts and Minnesota; the Canadian provinces of Alberta, British Columbia, Ontario, and Quebec; the Basque region of Spain; and Dubai, United Arab Emirates. For more information on TIMSS, see supplemental note 5.