Name: ______________________
Graphing Earth’s History
7th/8th Grade Science
Learning Targets
#7: In your graph and your conclusions, analyze and interpret data for patterns in the fossil record that document the
existence, diversity, extinction and change of life forms throughout the history of life on Earth.
#9: In your conclusions, discuss how living organisms have played many roles in the earth system such as: affecting the
chemical elements that make up the atmosphere, producing some types of rocks, and contributing to the weathering of rocks.
Draw Conclusions
To show proficiency (a 4), answer the following questions on a left side page.
1. Look back at the predicted graph you drew. Compare it to the graph of actual data.
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What differences do you notice? What knowledge do you have that accounts for these similarities?
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What similarities do you notice? What knowledge do you have that accounts for these differences?
2. What gas has made up the largest portion of the Earth’s atmosphere for most of Earth’s history?
3. What gas increased dramatically over the history of the Earth?
4. What gas did not appear in any measureable amount until about 2.0 billion years ago?
5. What gas has been almost nonexistent in the atmosphere since about 3.0 billion years ago?
6. Which gas appeared in the atmosphere about the time that limestone deposits became common?
7. What event is correlated with the increase in atmospheric oxygen (and the decrease in carbon dioxide)?
Why might these events be correlated?
8. If the natural trend that you see in the graph continues, how might Earth’s atmosphere change in the next
500 years?
9. If human activity continues at its present rate, what will probably happen to the levels of carbon dioxide
and other gases?
To show evidence of mastery (above a 4), respond to the following questions.
1. What event in Earth’s history probably had the most effect on the composition of the atmosphere? Why?
2. The atmosphere of Venus and Mars are mostly carbon dioxide, while the atmosphere of Earth is mostly
nitrogen and oxygen. Why is Earth’s atmosphere different?
3. Hydrogen gas is practically nonexistent in the atmosphere today. Looking at the physical and chemical
properties of hydrogen can help explain why. What do you think was the cause of the elimination of
hydrogen from Earth’s atmosphere by about 2.5 billion years ago?
4. How do the changes in the atmosphere’s composition throughout Earth’s history illustrate the Gaia
Hypothesis? Read about the Gaia Hypothesis in the handout provided before responding to this question.
Submit your graph and your responses to the “Draw Conclusions” questions for summative
assessment by __________________________________________.