The broad purpose of the Third International Mathematics and Science Study (TIMSS) Video Study was to investigate and describe Year 8 mathematics and science teaching practices in a variety of countries. More specific aims included : development of objective, observational measures of classroom instruction to serve as quantitative indicators of teaching practices; comparison of teaching practices to identify similar or different lesson features across countries; and development of methods for reporting results of the study, including preparation of video cases for both research and professional development purposes. Australia's goals for participating in the study emphasised : obtaining authentic and rich information on mathematics teaching in Australian lower secondary schools; ascertaining the extent to which Australian mathematics teaching in 1999 reflected emphases in curriculum documents developed during the 1990s; viewing Australian teaching practices in relation to those Asian countries that were among the highest achieving countries on the TIMSS 1995 mathematics assessment; assembling an information base of classroom practice for professional development purposes; and taking advantage of the opportunity to learn from the study's innovative methodology. A secondary objective in Australia was to examine differences in content and pedagogy between high and low achieving classrooms.