An explanation is a statement or set of statements that clarifies the reasons, causes, context, or principles that underpin a particular phenomenon. The word derives from the Latin term explicatus, which means to provide reasoning for. Explanations are central to the discipline of science as one of the goals of the discipline is to provide explanations that lead to a deeper understanding of various phenomena. In plain English, explanations elucidate why things work, what something is, or how things happen. They often provide cause and effect relations, include a time sequence, and use action verbs. An explanation usually has five parts: (i) naming or specifying the concept, (ii) describing elements or components of the concept in an appropriate order, (iii) explaining how the elements relate or connect to each other, (iv) providing an example, and (v) summarizing with a concluding statement. It is a fundamental expectation in most school science curricula that students should be able to explain science concepts. For example, the Australian National Curriculum states: "Science provides an empirical way of answering interesting and important questions about the biological, physical and technological world. The knowledge it produces has proved to be a reliable basis for action in our personal, social and economic lives" (ACARA 2012, p. 3). Similarly, the US National Science Education Standards calls for more than "science as process," in which students learn such skills as observing, inferring, and experimenting. Inquiry is central to science learning. When engaging in inquiry, students describe objects and events, ask questions, construct explanations, test those explanations against current scientific knowledge, and communicate their ideas to others. They identify their assumptions, use critical and logical thinking, and consider alternative explana- tions. In this way, students actively develop their understanding of science by combining scientific knowledge with reasoning and thinking skills.