Book excerpt: What is the cocktail of successful schools and their leaders? They are restless. There is a paradox at their core: they are very secure in their systems, values and successes, yet simultaneously seeking to change and improve. These schools look inwards to secure wise development; they look outwards to seize innovation which they can hew to their own ends and, importantly, make a difference to the children and students they serve. This book is written with the certainty that whatever the quality of an education system and its schools at a given point in time, we shall strive to improve them, in the knowledge that perfection lies just around the corner. That is the human condition. That is the international imperative. That is the restless school. What is the cocktail of success in memorable classrooms and great schools? What powers the engine of The Restless School? Should we judge schools by their values added or their value-added? Why do schools falter and fail? What might Excellence As Standard look like across global school systems? What does the 21st century have in store for schools and school leaders? Rooted in the experience of decades of education leadership, Roy Blatchford answers these key questions as schools everywhere seek to be world-class.