Title: Geologic Time Scale II
Author: Denise Deja, Lake Geneva Middle School, 600 Bloomfield Rd., Lake Geneva, WI 53147
Grades: 7-8 (Spiraled)
Overview of Lesson: Students will review the geologic eras
(from seventh grade) and begin to focus on the periods. The students will have an
understanding of the different periods. Students will be assigned plants and animals to
research and find the period in which they were first introduced.
Suggested Time: 5 to 6 periods of 45 minutes
Students' Prior Knowledge:
This activity will be completed at the beginning of eighth grade. At the end of seventh grade,
students will have completed an activity introducing the various geologic time scales and the
eras. To access what the students recall from the previous year’s activity, as well as any
other knowledge they may have about the
Geologic Time Scale, the students will be given the
Students will be creating their own geologic time line by gathering information from texts,
internet sites, periodicals, the teacher and any other relevant sources. The students will be
researching how many years ago certain plants and animals first existed.
Scientists have studied the ages of fossils in a couple of different ways. First, particular
isotopes have half-lives which can be used to determine a rock’s age if they contain those
elements. This is studied using very complex laboratory applications. Second, scientists have
used Carbon-14 to date organic materials.
Materials (per group of 4-6 students):
Materials (per student):
Refer to "Materials per student" section.
- 5 meters of copy paper taped together or 5 meters of adding machine tape
- meter stick
- clear transparent tape
- Begin the activity with the Geology Questionnaire. It is
important that the students are reminded that the question will not be graded.
- After the questionnaire has been given and discussed, the students will be introduced to
the periods within the eras in the geologic time scale.
The Geologic Time Scale will be used as a visual.
- One the students have a basic understanding of the periods, the students should be broken
up into groups of about four. Once they are split up, each student should receive an
Investigating Prehistoric Plants or Animals
handout, which includes the directions for the
research. The students will be required to find out when the plants and animals first
inhabited the earth. In other words, in what period is the earliest recorded fossil?
Some other basic information may be required, depending on the individual teacher’s request.
The teacher may also wish to provide the students with pictures of the plants and animals, as
opposed to having them create their own. If the students are creating their own pictures,
they should be given sheets of paper that will fit on the size time line the teacher is having
- When the students have completed researching, they will come together with the group to
create a geologic time line. (See instructions for constructing the time line under Making a
Geologic Time Line in the Student Activity: Geologic Time Scale I. After the
students have created their time line, each student will share the information that they have
gathered with their group. Then the pictures of the plants or animals that they have
researched will be placed on the time line in the proper period.
- After the group has their time line put together, they will pair up with another group to
compare their time lines. If there are any discrepancies, the groups should discuss them.
- Next, the students will compare their geologic time line with the teacher’s. The teacher
will discuss the proper placement (using the
Prehistoric Plants and Animals sheet) while talking
more about the periods. The most important things to describe to the students
are the major events or species that were found in each period.
- When the students have become more familiar with the periods, the teacher may wish to use
the Geologic Chart worksheet. The students can
complete it with or without using the Geologic Time Scale,
depending on what the teacher would like to assess.
- Write an essay about one of the plants or animals researched and present it to the class.
- Instead of using a time line to show the eras, the students could us a clock to show the
eras and periods. By using the ratio 24 hrs. = 4.6 billion years, they could calculate the
hours needed for each era and period.
eras, periods, fossils, extinct, inhabit
Math: The students will be measuring and making various calculations for creating the
time line. Mathematical calculations may also need to be made to determine what period each
plant or animal belongs in.
Language Arts: The students will be doing research and citing sources. When discussing
the different periods, students will be learning new vocabulary.
Wisconsin State Science Standards:
Collect evidence* to show* that models* developed as explanations* for events were (and are) based on the evidence available to scientists at the time
Describe* how scientific knowledge and concepts have changed over time in the earth and space, life and environmental, and physical sciences
Identify* questions they can investigate* using resources and equipment they have available
Identify* data and locate sources of information including their own records to answer the questions being investigated
Analyze* the geologic and life history of the earth, including change* over time, using various forms of scientific evidence