Science education in the United States is in serious trouble. On the 2005 National Assessment of Educational Progress (NAEP) science exam, 4th graders were the only group of students who made progress. Eighth graders' performance remained stagnant, and that of 12th graders declined (National Center for Education Statistics, 2006a). International comparisons confirm the problem: Although U.S. students perform close to the international average in life sciences, they lag behind other countries' students in chemistry, physics, and earth science (National Center for Education Statistics, 2003).

Of the many steps needed to improve U.S. science education, none is more important than improving teacher training and preparation. Individual classroom teachers determine the quality of instruction that students receive. Many studies show a close correlation between student achievement in science and teacher preparation in science. For example, using longitudinal data, Monk (1994) found that the best predictor of student performance in science was teacher course-taking patterns: The more science courses teachers had taken in college, the better their students performed.