Students will see why scientists have divided the time scale into Eras, Epochs, and Periods and discover how the time scale is used. They will also learn how geologists determine the age of rocks by visiting the dating lab at Ohio State University. The video and computer animations will also allow students to explore how meteorites are used to help determine the age of the Earth. A teacher’s guide that includes a glossary of terms, suggested teaching activities, and a quiz is available on the producer’s website. Duration: 25 minutes.