This volume is a teacher's edition in a series of books that contain open-ended exploration activities and experiments. These activities allow and encourage students to set their own goals, use their own creativity and ideas, investigate the wonders of nature, learn about the workings of real businesses, and draw conclusions from their investigations of these real-life situations. Students participate in many explorations by first making things such as a geoboard or an adding machine and then using their creations to complete the exploration or investigation. The 40 activities are grouped under the National Council of Teachers of Mathematics' (NCTM) Curriculum. Standards of: communications, spatial sense, measurement, number sense, connections, estimation, and reasoning. Some activities include: Somewhere in Time: Making a Time Capsule; Tangram Puzzles; Exploring with Puzzles; The Pendulum Swings: Investigating Time and a Pendulum; Dot Bingo: Making and Playing a Game; Mosaic: Exploring Coordinate Planes; What Is Your Surface Area? Approximating Surface Area; Experimenting with Slant: Comparing Results. Each activity contains a teacher's guide that lists: goal, student objectives, guide to the investigation, and vocabulary, along with a description of the activity that includes: an introduction, purpose, materials needed, procedures, observations, conclusions, and suggestions for further study. (MKR)