Abstract
This seminar introduces international large-scale assessment research through two influential studies: the Programme for International Student Assessment (PISA) and the Trends in International Mathematics and Science Study (TIMSS). We explore what these assessments measure, why their designs differ, and how researchers use carefully selected samples, questionnaires, and statistical methods to investigate patterns across countries and over time. These rich datasets offer opportunities to study student achievement, engagement with science, learning opportunities, educational inequality, and pathways into further science education.

At the same time, international comparisons require careful interpretation. We consider whose knowledge is represented, whether questions have comparable meanings across cultures, who may be excluded from the data, and why statistical relationships do not necessarily demonstrate causation. No advanced statistical background is required. The seminar introduces the main ideas in accessible terms and considers how large-scale evidence could contribute to astronomy education research.

By the end of this seminar, participants will be able to:
• Explain the main purposes and designs of international large-scale assessments
• Describe opportunities for using large-scale assessment data in education research
• Recognise key methodological challenges and interpret findings from these assessments critically

Glossary terms:
• International large-scale assessment (ILSA)
• Programme for International Student Assessment (PISA)
• Trends in International Mathematics and Science Study (TIMSS)
• Representative sample
• Plausible values
• Cross-national comparability
• Multilevel analysis