How to improve mathematics learning is a major issue throughout the world. One potential source of such improvement is application of the increasingly realistic and encompassing theories of mathematical development that have been proposed in the past few years. In this talk, Professor Siegler will first review theoretical research on the development of numerical magnitude representations, then present evidence for the effectiveness of a numerical board game that applies the theoretical research to improving low-income urban preschoolers. numerical understanding, and finally describe extensions of the theory and research to fractions. There will be time for audience questions and discussion with Professor Siegler following the presentation. Originally submitted by: Sandra C. White