This is a must-read book for anyone involved in educational research. It will particularly appeal to students on research degrees and teacher educators, but also practitioners engaged in classroom research projects. We all want to enhance children and young people's learning experiences and this book is the ideal companion to help us reflect on rigorous ways of doing this. It takes the mystery out of randomised control trials, commonly regarded as the gold standard of research. This is not a stuffy, technical book purely for academics, but a thoroughly engaging read for all those serious about making a difference in the classroom. Both authors draw on their expertise to show that experimental research is nothing to be frightened of, but a key driver for professional development and school improvement. For teachers and leaders who want to give credible answers to inspectors who ask -˜How do you know?', read this book.