This book of activities was designed to provide students with the opportunity to create mental models of concepts in astronomy while using simple, homemade tools. In addition, these sequential, hands-on activities are to help students see how scientific knowledge is obtained. The introduction describes the rationale for the book and describes the prerequisite terminology and materials that will be utilized in the activities. Chapter 1 demonstrates three tools for measuring angles on the dome in the sky. These tools are used to determine the latitude and angular diameters of the sun and moon. Chapter 2 shows students how to build a sun compass to find true north, and in cooperation with one or more distant colleagues, to compute the circumference of Earth. Chapter 3 uses the moon's angular diameter and the size of the Earth found earlier, and a photograph of a lunar eclipse to calculate the moon's size and its distance from Earth. Chapter 4 enables students to measure the angular separation of the sun and moon in order to discover the distance between Earth and the sun. Chapter 5 uses the brightness of stars to suggest how far away they are and places the solar system in its proper context within the whole galaxy of stars. Worksheets for the activities are provided at the end of each chapter. Four appendices include a glossary, suggestions on how to nurture the student interest generated by these activities, derivations of the formulas utilized in the activities, and an answer for the problems posed in the worksheets. (Contains over 40 references.) (MDH)