A seeming anomaly appeared in the latest test results for fourth-graders in the Third International Mathematics and Science Study (TIMSS).

• In science, American fourth-graders placed second, behind Korea, out of 20 countries participating.

• In math, they scored eighth out of the 20.

• But in results released earlier on a TIMSS test of eighth-graders, U.S. students placed 28th out of 41 countries in math and 17th in science.

Educators are attempting to determine why the achievement levels of U.S. students fall so fast within four grades, and why the levels here fall more than in any other country.

Compared to students in other countries, American children get fewer new topics to learn over time.

• In U.S. math curricula and textbooks, about 25 percent of the topics studied in the eighth grade are new since fourth grade -- compared to 75 percent new material in most other countries.

• The same is true in science.

• While American schools don't make students focus on new topics, according to TIMSS analysts, schools in other countries focus on six or seven advanced math topics between fourth and eighth grades.

• American fourth-graders lagged in measurement, number sense and estimation -- perhaps because American students are twice as likely to use calculators, suggests TIMSS.

• In six of the seven nations that outscored U.S. fourth-graders in math, teachers of 85 percent or more of the students report never having the students use calculators in class.

Interestingly, the TIMSS report shows that class size does not have a strong bearing on results. The average South Korean class has 43 students -- and that country placed first in math.

Source: Editorial, "The Devil's in the Curricula," Investor's Business Daily, June 18, 1997.