Set up a carousel exercise with illustrations of representative flora and fauna for each era and period. As a class, brainstorm a list of reasons why a species could become extinct, and have students write a news report of the future, announcing the extinction of a present-day endangered species. This is a linear model of the geologic time scale made by marking the major events of earth history on adding-machine tape attached to the classroom wall, hallway wall, school field, or sidewalk. Ask them to illustrate their time scale with key organisms of each period, and suggest reasons for placement and location of geologic divisions. Have them then use the geologic time scale to represent ages in terms of eras, periods, epochs, and years.
Students use a fossil key to deduce the age of a rock sample containing a fossil.
Assessment strategies should require that students demonstrate a knowledge of the time scale's development, its significance, and its use in describing events in earth history. Require different groups of students to research and report on particular periods of geologic time. Have students write about what they learned from constructing a model of the geologic time scale, and note what they found surprising. Next Page Copyright 1996 . All Rights Reserved.