In addition to the following questions about TIMSS, more FAQs about international assessments are available at: http://nces.ed.gov/surveys/international/faqs.asp.
TIMSS operates on a 4-year cycle, with 1995 being the first year it was administered. For TIMSS 2007, countries in the Northern Hemisphere conducted the assessment between April and June, 2007. Countries in the Southern Hemisphere conducted the assessment in October and November, 2006. In both hemispheres the assessment is conducted near the end of the school year.