Have students count tree rings or the growth lines of a mollusc to find age by direct measurement. Have them deduce how this could be done with rocks. This organizer provides opportunities to assess the ability to use models in the context of geologic time. Assessment may also focus on the ability to make logical inferences based on indirect evidence, such as reconstructing past events and conditions from fossils. Have students model the radioactive decay of elements using 100 upright thumbtacks in a shoe box.
Students can record and graph the number of tacks remaining upright each time the box is shaken.
Collect the students' geologic timelines showing significant events in history. Check the accuracy of the positions and information of geologic eras, periods, and epochs. Provide a set of fossil specimens or photographs. Have students develop analogies of their own for illustrating geologic time. In small groups, students discuss one anothers' analogies and provide feedback on creativity, clarity, and accuracy.