Jeffrey E. Barrett is a Professor of Mathematics Education and also serves as an Associate Director of the Center for Mathematics, Science and Technology at Illinois State University. His primary research interests include the learning and teaching of the mathematics of measurement and geometry, the use of computer software to model mathematical ideas, and the professional development of teachers. Dr. Barrett is currently Principal Investigator of a four-year project, A Longitudinal Examination of Children’s Developing Knowledge of Measurement: Mathematical and Scientific Concept and Strategy Growth from Pre-K to Grade 5 in collaboration with Douglas Clements and Julie Sarama at the University at Buffalo, SUNY.