63 countries participated in TIMSS 2011 and even more participated in 2015. To ensure that data from TIMSS can be used to analyse trends over time the structure of the survey in 2015 was similar to that used previously.

The main data collection took place in spring/summer 2015 and the international data and report will be released in December 2016.

TIMSS sets high participation targets in order to ensure that data is of good quality and that valid comparisons between countries can be made. Sampled pupils complete a single test booklet containing items assessing knowledge and skills in mathematics and science. The item formats vary and include closed-response items, short-answer items and more extended items focussing on problem-solving and investigatory approaches in mathematics and science.

Findings from TIMSS are detailed. They include:

  • achievement data by subject and content domain within each subject, e.g. geometric shapes and measures in mathematics or physical science in science
  • achievement data by cognitive domain within each subject (knowing, applying, reasoning)
  • comparative data showing each country's achievement against that of other countries, by subject, content and cognitive domains
  • trend data showing each country's achievement over time by subject, content and cognitive domains
  • 'benchmark' data describing the achievement of pupils in different bands and the proportion of pupils in each achievement band for participating country
  • contextual information about characteristics of the national education systems, schools, teachers and pupils and their homes
  • relationships between contextual characteristics and achievement.