Activity 1.2:
Earth Timeline
TIME FRAME
2-3 class periods
OBJECTIVES
Students will be able to:
- develop an appropriate scale to measure Earth's history;
- demonstrate knowledge of major events in the Earth's history;
- develop a sense of the enormity of time involved in understanding the Earth's
history; and
- understand the short time period in which humans have been present on the Earth.
MATERIALS REQUIRED
- string
- meter stick
- 8.5x11" paper
- chalk, felt pens, or other marking material (stones, sticks, etc.)
- information sources for major historical events
- Global Change and Canadians
PROCEDURES
1. Read Chapter 1 of Global Change and Canadians. From the handbook, determine a length of time that would be appropriate for measuring the history of the Earth. (approx. 4.5 billion years).
2. Divide the class into groups. Brainstorm a list of events that should be included on an Earth history timeline. This could include the age of dinosaurs, the earliest known human activity, the last ice age, the beginning of civilization, the Roman era, the Christian era, the Middle Ages, and so on until the present. Students will conduct research in the library to determine the dates of the events listed in the brainstorming session.
3. Problem solving: Students will attempt to draw a timeline on a sheet of 8.5x11" paper that shows the 4.5 billion year history of the Earth. They will attempt to mark the events listed in the brainstorming session on the paper timeline.
- Discuss: Is the paper timeline an appropriate medium for marking an Earth history
timeline? Can you use it to show human activity?
- Problem solving: What would be an appropriate place to measure the Earth's
history? What would be an appropriate scale? Students can offer
suggestions; the class can then create the timeline according to the best
suggestions.
- Possible solution: Using a scale of 1cm=1million years, the class can use string and
a meter stick to measure the history of the Earth (4.5 billion years) in a large
physical area, such as in the school playing field. Mark the major Earth
events along the string with markers, such as stones or sticks. Label each marker
with a simple sign created with paper and felt pens.
ASSESSMENT
This activity is an attempt to develop an understanding of the enormity of the Earth's history, and of the short time that human activity has had an effect upon the Earth. If students worked in groups, cooperative learning assessment techniques are applied. Assessment must focus on the objectives of the lessons:
- Did students develop an appropriate scale to measure the history of the Earth?
- Did students create an Earth history timeline?
- Did students discover major events in the Earth's history? Did they mark those
events on the timeline in the appropriate places?
- Did students discuss and display an understanding of the enormity of the Earth's
history and the short time period of human activity?
EXTENSION
In Global Change and Canadians: A Teacher's Guide various activities are suggested that might help students relate the short time period of human activity to the overall and long term changes to the global ecosystem. Questions that should be kept in mind for discussion throughout these activities include focusing on changes that have occurred to the global system before and during the "human activity" time period.
Activity 1.7: Ecosystem in a Jar
TIME FRAME
6-10 weeks or longer
OBJECTIVES
Students will:
- create an Earth "biosphere" in a jar,
- document the changing conditions, and
- compare their biosphere to planet Earth.
MATERIALS REQUIRED
- glass jars with lids
- biosphere materials
PROCEDURES
Pre-Activity Preparation
1. Each student should bring a medium or large glass jar to class.
2. Collect the biosphere material from a swamp or irrigation ditch, or make your own combination using water, plant material, or sand. Bring the material to the classroom or arrange a short field trip for your students to collect their own material.
ACTIVITY
1. Define the Earth as a biosphere- an interdependent system, which is self-adjusting and self-balancing. Explain that each student or group of students will be creating their own biosphere in a jar and monitoring the changes.
2. Brainstorm with the students and write on the blackboard the basic elements necessary for life on the Earth (air, water, food, energy [sun], and space).
3. Students can now create their own biospheres by adding the necessary ingredients to their jar. Students can work in groups, partners, or individually. Place the jars on a window ledge or near some light source.
4. Students should keep a journal and record the changes to their biosphere every other day for a one month period.
[Sidebar:
Depending on the mix of ingredients in the biosphere jars, changes may occur quickly or slowly. Each jar will exhibit different changes. Use this on-going classroom experiment as an opportunity for "teachable moments". Allow the changes to prompt students’ questions and class discussions about what may have caused a certain change and what might occur because of those changes.]
ASSESSMENT
This activity is a whole unit activity, and can be used to build experimentation, scientific journal keeping, comparison activities, and more. Assessment must be based on the objectives of the activity, and should also be extended to include activities generated by the teacher over time.
EXTENSION
1. Keep a few biosphere jars aside for specific tests. Place a dark cloth over one jar for 3-4 days. Compare results to the scenario of a "nuclear winter". Swirl the mud around in another jar as if volcanic ash was covering the Earth. What are the results? Ask students about other experiments the class can conduct.
2. Point out that changes occurring in the jars are part of the self-regulating process of the biosphere. If the population of crustacea becomes too large and consumes all the available resources, what are the results? Define the steady-state or balanced condition, which the surviving biospheres will eventually reach as sustainable. Compare biosphere jars to planet Earth. How can a growing world population and limited resources affect the sustainability of life on Earth.
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