The "Framework" (NRC 2012) and "Next Generation Science Standards" (NGSS Lead States 2013) require science teachers to think differently. Specifically, NGSS's performance expectations now require that three domains (disciplinary core ideas (DCI), crosscutting concepts (CCC), and scientific and engineering practices (SEP)) be seamlessly integrated into teaching for each grade level. Great strides have been made in developing curriculum and instructional practices that assist teachers in guiding students to meet these performance expectations. For example, NGSS's "Classroom Sample Tasks", provide lesson plans that support student achievement of performance expectations through integrated project- and problem based activities. Despite these resources, clear strategies for assessments, particularly formative assessments, remain elusive for practicing teachers. In an attempt to provide assessment guidance for these NGSS goals, the authors of this article illustrate how formative assessments can be organized to support learning in all three domains using three models: Concurrent, Sequential, and Embedded. Table 1 summarizes the three models, including guidance of when each may be most useful. The remainder of the article shows what these models may look like in practice, including an example with a specified performance expectation and tips for teachers.