The current wave of science education reforms emphasizes more equitable opportunities for students as they learn disciplinary core ideas and apply crosscutting concepts by engaging in the practices of scientists. Formative assessment—the assessment teachers and students conduct while learning is in progress—also needs to shift to support this vision. This book combines three-dimensional science learning, sociocultural theories of learning, and science for justice and equity to provide a comprehensive picture of formative assessment for today’s K–12 science classroom. Using practical examples and strategies, the author provides guidance for classroom teachers around formative assessment task design that centers students’ interests and builds on the resources they bring to school. The text explores the different enactment approaches teachers can use to prioritize and respond to students’ ideas as they are learning. It also offers approaches to, and resources for, professional learning that support teachers as they engage in formative assessment for ambitious science instruction.