This handbook has been structured to provide teachers (K-2) with the most recent research on problem solving. It contains information and practical applications which deal with the key concepts of problem solving in mathematics. The handbook consists of four sections. The first section establishes the background and gives the purposes of the handbook. The second section provides a general overview of problem solving. It identifies two types of problems and presents the stages of thinking when solving a problem. This section also describes the key problem solving strategies which are commonly used in the primary grades. The third section includes the main body of the handbook containing a variety of activities for each grade level. Charts interface the activities with mathematical topics and problem solving strategies for each grade level. The last section contains a bibliography of 18 items which can be used as supplementary resources. (MVL)