The National Assessment of Educational Progress (NAEP) and the Trends in International Mathematics and Science Studies (TIMSS) are two prevalent standardized tests, and we compare the results in 4th grade mathematics between the U.S and other countries. The NAEP mathematics assessment is the only federally authorized and continuing nationwide assessment of student mathematics achievement. It serves as a source of information to measure student performance. TIMSS standards have affected the overall quality and performance of national educational systems in participating countries, and they also have influenced school resources and teaching methods. Analysis of the latest national and international performances reveals consistently average U.S. results on both assessments. Moreover, the dimension of the Numbers content is the weakest. This is a disconcerting result, given the fact that math instructions per week were increased more than any other subject, and more attention was paid to number properties and operations than any other content area in primary education. The book discusses problems related with school organization, curriculum, methods of instruction among others.