TIMSS attempted to assess different features of student learning and hence one can reasonably expect different findings from them.

In general terms, TIMSS sought to find ‘what students know. These two perspectives are neither ‘better’ nor ‘worse’. Rather they are different, and each has importance as a learning outcome of the study of science at school.

The data gathered in the TIMSS project related to the intended curriculum (the curriculum specified by the system or other body), the implemented curriculum (the curriculum as taught by teachers, the nature of actual classrooms), and the attained curriculum (what students have learned).

The intentional differences in the projects are evident in how each project structured and developed its tests.