This book demonstrates the use of an 80mm refractor and shows how it can be used as a real scientific instrument. The author is an experienced small telescope user and an astronomy educator, and he provides step-by-step instructions for numerous scientific activities. Users will find many activities and projects suitable for an 80mm refractor or 90mm reflector or Maksutov that have not been published elsewhere. Emphasis is on measurement and discovery activities rather than on casual observing. This book will provide amateur observers with the knowledge and skill that will help them make genuine contributions to the field of astronomy.