In this module, we will explore the links between biodiversity and the ecosystem. In doing this, we will also practice methods of scientific inquiry, moving from theory or observation to a question and hypothesis and the design of an experiment. We will begin with discussions of BEF, including a history of the field and the controversies surrounding it. Then we then analyze a dataset of tree diversity and ecosystem properties compiled across tropical forests. In teams of two, you will formulate a question and hypothesis and analyze the data. Did you find support for your hypothesis? What new question has arisen through your analysis? What kind of data would you need to answer this question? You will then propose an experiment or observational study in order to answer this question. At the end of the module, you will present your journey of discovery, and how you progressed from a question, theory or observation to a new question and a proposed experiment or observational study. Details of the module are below.