Enter Amanda Ripley's "The Smartest Kids in the World," a book as readable as it is important. The author follows three American students to foreign lands and arrives at a bracingly simple conclusion. Despite different cultures and approaches, today's best-performing systems share one thing: "a pervasive belief in rigor." Class size? Spending per capita? Cutting-edge IT? All basically noise. What matters are shared expectations that tests will measure real results and policies that attract, train and pay for top teaching talent. Most inspiring is Ms.