This unit is 1 of 12 developed for the university classroom portion of the Mathematics-Methods Program (MMP), created by the Indiana University Mathematics Education Development Center (MEDC) as an innovative program for the mathematics training of prospective elementary school teachers (PSTs). Each unit is written in an activity format that involves the PST in doing mathematics with an eye toward application of that mathematics in the elementary school. This document is one of four units that are devoted to mathematical topics for the elementary teacher. In addition to an introduction to the unit and some perspectives on problem solving, the text has six activity sections titled: In Search of a Strategy; Looking for Another Strategy; To Find a Third Strategy; Now Try Your Hand; Reflection on Your Experiences; and Helping Children Solve Problems. (MP)