"A Framework for K-12 Science Education" identifies eight science and engineering practices for K-12 classrooms. These practices, along with core ideas and crosscutting concepts, define the nation's learning goals for science. The practices outlined in the framework are: (1) Asking questions and defining problems; (2) Developing and using models; (3) Planning and carrying out investigations; (4) Analyzing and interpreting data; (5) Using mathematics and computational thinking; (6) Constructing explanations and designing solutions; (7) Engaging in argument from evidence; and (8) Obtaining, evaluating, and communicating information. In this article, the authors examine the sixth and seventh practices concerning explanation and argumentation, respectively. The two practices depend on each other: For students to practice explanation construction, they must also engage in argumentation. Here, the authors first define argumentation and explanation individually and then explore their relationship in classroom examples. (Contains 1 figure.)