Douglas Clements, PhD, is the author of Early Childhood Mathematics Education Research: Learning Trajectories for Young Children. Dr. Clements is widely regarded as a major scholar in the field of early childhood mathematics education, one with equal relevance to the academy, to the classroom, and to the educational policy arena. At the national level, his contributions have led to the development of new mathematics curricula, mathematics software, teaching approaches, teacher training initiatives, and models of “scaling up” interventions. He has also had a tremendous impact on educational planning and policy, particularly in the area of mathematical literacy and access. Dr. Clements has served on President Bush’s National Mathematics Advisory Panel, the National Research Council’s Committee on Early Mathematics, and the National Council of Teachers of Mathematics National Curriculum and Principles and Standards committees. He is presently serving on the Common Core State Standards committee of the National Governor’s Association and the Council of Chief State School Officers, helping write national academic standards.