Global Evidence of Wide Variability in Mathematics Achievement within Classrooms

The First Global Analysis of Within-Classroom Achievement Variability Using TIMSS 2023

Abstract

Teachers teach students in classrooms; therefore, knowing how diverse their classrooms are in terms of student achievement is critical for educational policy and practice. This study provides the first global analysis of mathematics achievement variability within intact grade 4 classrooms using data from the Trends in International Mathematics and Science Study (TIMSS) 2023. Analysis of variance (ANOVA) served to determine the proportion of total mathematics score variance that lies (i) within classrooms, (ii) between schools, and (iii) between classrooms within the same schools. Descriptive statistics were used to further quantify the variability of mathematics scores existing within the classrooms. Results showed that in 60 of the 63 participating countries and education systems, within-classroom variance exceeded variation between classrooms and schools. On average, 70% of the mathematics score variance was within classrooms, considerably more than the 30% found between classrooms and schools. The spread of achievement in an average classroom covered three full standard deviations of the national achievement distributions. This was equivalent to almost five years of primary school. Most classrooms contained students from every TIMSS achievement level. On average across all entities, 10% of the students were at the Advanced level, 24% High, 29% Intermediate, 21% Low, and 16% at the Below Low level. This study challenges the perception that the main differences in student achievement are between schools instead of within classrooms. It also challenges the vision that in a high quality and egalitarian school system, all students have similar achievement levels. Classroom heterogeneity is a global characteristic of primary education. The findings suggest that policies aimed at improving learning should place greater emphasis on supporting teachers to address within-classroom heterogeneity. For instance, by introducing more flexible curricula and differentiated instruction, countries may be in a better position to address the learning needs of all their students.