Why haven’t our classrooms been transformed by that same pattern of improvement and innovation that we take for granted in every other aspect of our lives? It’s not that we haven’t tried. Schools have adopted all sorts of new technologies over the years, from projectors, to personal computers, to “smart” white boards. The trouble is that none of these new inventions has improved outcomes – measurable outcomes – on a global scale. Let’s take a look at something. American test scores at the end of high school have been flat since we started keeping track of them all the way back in the early 1970s, and the same thing is true in most other countries as well. Basically, educational quality has been stuck in the era of disco and leisure suits for 40 years, while the rest of the world has passed it by. Classrooms and clothes look a little different now than they did back then. But we’ve changed the trappings of education without really improving the substance. The best schools haven’t grown and taken over the less successful ones. The best teaching methods haven’t been replicated on a mass scale. And while our top athletes and pop stars reach huge audiences, our greatest teachers seldom reach more than a few dozen kids at a time, despite all our technological advances. Why not? That’s the question at the heart of this series: why doesn’t excellence scale up and spawn imitators in education, the way it does in other fields? We’ll travel the globe in search of an answer to that question. And we’ll take a few detours along the way, because the shortest route isn’t always a straight line.