It is not possible, a priori, to say that one mathematical topic is more complex than another. However, we can judge how advanced a topic is based on its placement in mathematics curricula around the world. We made use of the TIMSS curriculum analyses conducted by William Schmidt and his colleagues at Michigan State University to estimate the average level of mathematical content in the videotaped lessons studied in each country.

The curriculum analysis asked experts in the 41 TIMSS countries to identify the grade level at which various topics in the TIMSS framework were most emphasized in their country. In this way, the grade level at which most countries focused on a particular topic was determined. The content of each lesson in the video study was coded according to the same framework, and the topics taught were compared to the international average.

The average grade level of topics covered in the video sample is shown in the graph. By international standards, the mathematical content of US lessons was at a seventh-grade level on average, whereas German and Japanese lessons fell at the high eighth- or ninth-grade levels.