<p>Students’ opportunity to learn (OTL) in mathematics in terms of the curriculum they experience in school has largely been examined in relation to subsequent student attainment, with less attention paid to whether prior attainment is itself associated with later OTL. Furthermore, existing international studies have operationalised OTL in various ways, yet the relationship between prior attainment and OTL remains underexplored across these operationalisations and educational contexts. This study examines whether class-average prior attainment is associated with different operationalisations of OTL in mathematics. Secondary data analysis was conducted using data from the Global Teaching InSights video study of the teaching of quadratic equations across seven countries and jurisdictions. This analysis drew on student-reported, teacher-reported, and observational measures of OTL, focusing on content coverage and instructional quality. Multilevel and linear regression models were used to explore patterns of association between class composition and OTL. Associations between class-average prior attainment and OTL were modest and varied across contexts and operationalisations of OTL. Relationships with prior attainment differed between student-reported OTL, teacher-reported and observational measures, while class heterogeneity was more strongly associated with instructional quality than with content coverage. These findings highlight the importance of considering multiple operationalisations of OTL and suggest that relationships between prior attainment and OTL are context-dependent.</p>