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…

This article explores the factors that contribute most to the Iranian students' mathematical achievement using the Third International Mathematics and Science Study (TIMSS) 99 data. Mathematics achievement involves a complex interaction of factors that have specific direct effects and/or indirect effects through other factors on school outcomes.…