Teachers and teacher educators interested in synthesizing their current practice with new mathematics standards will welcome this highly useful volume. Author Mary Kay Stein and her colleagues at the QUASAR Project at the University of Pittsburgh present prevalent cases of mathematics instruction drawn from their research of nearly 500 classroom lessons. The Mathematical Tasks Framework, developed by the authors and explained thoroughly in the book, offers teachers and teacher educators the means to evaluate instructional decisions, the choice of materials, and learning outcomes, and the case studies afford readers the opportunity to ground these ideas in actual classroom practice. Readers will gain insight about how to foster a challenging, cognitively rich, and exciting classroom climate that propels students toward a richer understanding of mathematics. “If every teacher and teacher educator took the opportunity to study and discuss these cases, students everywhere would know and value mathematics as the national standards have envisioned.”—Susan Loucks-Horsley, Director of Professional Development for the National Institute for Science Education “The power of case discussions can be fully realized using this book as a tool. Equally important, teachers will be highly motivated because they see their own practice mirrored in the cases.”—Carne Barnett, WestEd, San Francisco, CA