This expanded and updated second edition book is written for scientists who want to learn more about how science education research is done and how to get started in discipline-based education research. It provides the reader with an introduction to the philosophical and practical differences between more familiar traditional scientific research and the more unfamiliar domain of sociological research. Readers will learn about the most robust ideas in education research, which serve as jumping off points in their new forays into the realm of discipline-based education research. Quantitative, interpretive, and action research methods are introduced with real-life, easy to follow examples. The authors, long-time contributors to the science education community, provide rubber-meets-the-road guidance to both first-time and experienced researchers, to get projects off the ground with the goals of improving classroom practice and contributing to the knowledge base on the teaching and learning of science. Discipline-based education research is much like traditional scientific research in that using different instruments sometimes results in unexpected answers. As an example, the cover image uniquely reveals vastly different information about flowers when viewed in visible light (upper left) and in ultraviolet light (lower right). In much the same way, carefully planned and well executed discipline-based education research using a variety of research lenses has the ability to yield unexpected insight into teaching and learning that can benefit all of us.