Students estimate the number of civilizations in the galaxy by first estimating the number of craters on the Moon and then by performing estimates of multiple-variable systems culminating in the use of the Drake Equation. In this three-part activity, students use estimation techniques to describe complex situations. By completing this acitivity, the learner will: use estimation techniques to describe complex situations. estimate the number of craters on the Moon. estimate the portion of the population that match given characteristics. answer questions about how their estimates change with alternatively defined variables. utilize a form of the Drake Equation to estimate the number of communicating civilizations that exist in the Milky Way Galaxy. examine the range and definition of each variable comprising the Drake Equation and evaluate how changes in the variables influence their result. National Science Education Standards National Mathematics Education Standards Materials and Technology Scientific Background Activity 1: Write and carry out a step-by-step plan for estimating the number of craters on the Moon that are larger than a football field. Activity 2: Estimate the portion of a population that match given characteristics and answer questions about how their estimates change with alternatively defined variables. Activity 3: Complete and use a table of values to solve the Drake Equation in order to estimate the number of intelligent civilizations in the Milky Way. Activity 1: Exploration-How many craters are on the Moon? Activity Page One gives students a close-up photograph of a small portion of the Moon's surface. Using the scale provided on the image, students count the number of large craters in the image and extrapolate to find the number of such craters on our Moon. Activity 2: Concept Introduction-Making Complex Estimates. Activity Page Two gives students a list of variables that describe a particular population of students. Students estimate the portion of the population that match the given characteristics and answer questions about how their estimates change with alternatively defined variables. Activity 3: Concept Application-Using The Drake Equation. Activity Page Three allows students to utilize a form of the Drake Equation to estimate the number of communicating civilizations that exist in the Milky Way Galaxy. Students examine the range and definition of each variable comprising the Drake Equation by using the Drake Equation Background Information Sheet and evaluate how changes in the variables influence their result. Assessment