This innovative text teaches elementary school students the techniques of critical thinking and problem solving and applies those methods to mathematical word problems. It supplements traditional fourth, fifth, and sixth grade textbooks and increases students' thinking and problem solving abilities. Students are taught the fundamentals of these processes by applying them both to simple and multi-step problems which are provided. These problems -- many written by elementary school pupils --gradually increase in difficulty, making learning both fun and stimulating. Special attention is given to typical errors and sources of conceptual difficulty.