"TIMSS is used to compare over time the mathematics and science knowledge and skills of fourth- and eighth-graders. TIMSS is designed to align broadly with mathematics and science curricula in the participating countries. The results, therefore, suggest the degree to which students have learned mathematics and science concepts and skills likely to have been taught in school. In 2011, there were 54 countries and 20 other educational systems that participated in TIMSS, at the fourth- or eighth-grade level, or both.
The results show improvement at grade 4 in reading since 2006, when PIRLS was last administered, and in mathematics since 2007, when TIMSS was last administered. Eighth-graders’ average scores held steady in both mathematics and science since the last TIMSS administration in 2007, as did fourth-graders’ average scores in science." IES Newsflash & NCES Statement on PIRLS 2011 and TIMSS 2011
