Does instructional clarity moderate the relationship between socioeconomic status and student achievement? A comparative analysis based on the TIMSS 2023 data

Reducing the effect of social status on learning outcomes constitutes one of the crucial challenges for contemporary education systems. This study sought to determine whether instructional clarity, as a teaching quality dimension, could moderate the effect of socioeconomic status (SES) on student achievement. The analysis was based on TIMSS 2023 data collected in 29 European education systems. The study examined a simple moderation model, with instructional clarity moderating the relationship between SES and achievement in mathematics and science tests. The results showed that the strength of the SES-achievement correlation varied across education systems, mostly proving moderate. Instructional clarity showed the potential to moderate the SES-achievement relationship, although in different ways across different education systems. In the ones with less pronounced educational inequalities, greater clarity weakened the SES achievement correlation, with students from the lowest SES backgrounds benefiting most from high instructional clarity. Conversely, in systems with more pronounced inequalities, instructional clarity proved able to even strengthen the SES-achievement correlation in the case of mathematics. The compensatory potential of high-quality instruction is shaped by the wider educational and social contexts. This has significant implications for inequality-reducing education policy measures.