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 an abacus or a three-dimensional model 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: Fingerprint Fun: Comparing Characteristics; The Ambitious Architect: Building with Different Shapes; Boat Races: Finding the Formula for Speed; I Forgot Your Birthday: Using the Calculator; Patterns in Art and Other Places: Exploring Tessellations; Twinkle, Twinkle, Many Stars: Estimating How Many Stars Are in the Sky; and It Is, Or Isn't It? Identifying Figures from Characteristics. 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)