This activity will help students to have a better understanding of the basic principles used to determine the age of rocks and fossils. It consists of several parts: to have students determine relative age of a geologically complex area, to familiarize students with the concept of half-life in radioactive decay, to have students see that individual runs of statistical processes are less predictable than the average of many runs, and to demonstrate how the rate of radioactive decay and the buildup of the resulting decay product is used in radiometric dating of rocks. Students learn to use the principles of determining relative age to show how ages of rocks and fossils can be narrowed even if they cannot be dated radiometrically.