This brief examines Trends in International Mathematics and Science Study (TIMSS) science achievement of the 20% highest and the 20% lowest performing fourth and eighth graders in 11 countries. To do so, the authors compare achievement distributions across countries, using measures of relative equality within countries. Such an examination…

The International Association for the Evaluation of Educational Achievement's (IEA) mission is to enhance knowledge about education systems worldwide, and to provide high-quality data that will support education reform and lead to better teaching and learning in schools. In pursuit of this aim, it conducts, and reports on, major studies of student…