Download TIMSS 2019 Assessment Design (pdf)
Student Populations Assessed
TIMSS assesses the mathematics and science achievement of students in their fourth and eighth years of formal schooling. Participating countries may choose to assess one or both populations, according to their policy priorities and resource availability. Because in TIMSS the number of years of formal schooling (four or eight) is the basis for comparison among participating countries, the TIMSS assessment is targeted at the grade levels that correspond to these. The TIMSS target populations are defined as follows:
- At the fourth grade, the TIMSS target grade should be the grade that represents four years of schooling, counting from the first year of ISCED Level 1.
- At the eighth grade, the TIMSS target grade should be the grade that represents eight years of schooling, counting from the first year of ISCED Level 1.
ISCED is the International Standard Classification of Education developed by the UNESCO Institute for Statistics and provides an international standard for describing levels of schooling across countries (UNESCO, 2012). The ISCED system describes the full range of schooling, from preprimary (Level 0) to doctoral study (Level 8). ISCED Level 1 corresponds to primary education or the first stage of basic education. Four years after the beginning of Level 1 is the fourth year of formal schooling and is the target grade for the fourth grade TIMSS assessment. This also is the fourth grade in most countries. Similarly, eight years after the first year of ISCED Level 1 is the target grade for eighth grade TIMSS, and is the eighth grade in most countries. However, given the cognitive demands of the assessments, TIMSS wants to avoid assessing very young students. Thus, TIMSS recommends that countries assess the next higher grade (i.e., fifth grade for fourth grade TIMSS, and ninth grade for eighth grade TIMSS) if, for fourth grade students, the average age at the time of testing would be less than 9.5 years, and, for eighth grade students, less than 13.5 years.
To represent the target population with an acceptable margin of error while keeping the assessment burden on schools and students to a minimum, each country selects a nationally representative probability sample of students at each grade. The basic TIMSS sample design consists of at least 150 schools and one or more intact classes per grade, for a student sample of approximately 4,000 students in each country.