The global rankings are the result of two studies - the Trends in International Mathematics and Science Study (TIMSS) and the Progress in International Reading Literacy Study (PIRLS).
The TIMSS is produced every four years while the PIRLS is published every five years, but this is the first time Northern Ireland has taken part in the test results study.
The IEA is probably best known for its Third International Mathematics and Science Study (TIMSS), an international large-scale assessment of learning outcomes (ILSA) for primary school learners in science and mathematics, as well as for PIRLS (Progress in International Reading Literacy Study).