This publication is designed to extend and strengthen the computational skills and mathematical understandings of children in Grades 2 and 3. It presents an overall scope and detailed sequence for implementation by teachers and supervisors, based on the modern program introduced in pre-kindergarten, kindergarten and first grade classes. The scope and sequence for this publication is presented in the form of units which are organized around four central themes--(1) Sets, Number, and Numeration, (2) Operations, (3) Geometry and Measurement, and (4) Problem Solving. The sequence is structured to provide a spiral or cyclic approach for presentation of the concepts and skills. (RP)