Former math teachers Tobey, a mathematics associate at the Education Development Center, and Fagan, a curriculum design associate at the Center, present 20 formative assessment probes aligned with the Common Core State Standards for teachers of grades K-2 to use to identify students' understandings and misunderstandings of key math concepts and make appropriate instructional choices. The probes consist of short sets of diagnostic questions related to counting and cardinality, number and operations in base ten, operations and algebraic thinking, measurement and data, and geometry. Each includes discussion of their purpose, structure, and development, as well as teacher notes for research and instructional strategies. The introductory chapter details their process and design and the development of an action-research structure. They end with instructional considerations, examples from practice to show how the probes can be used in the classroom, and discussion of how they can support proficiency with the Common Core's Mathematical Practices. Annotation ©2013 Book News, Inc., Portland, OR (booknews.com)