| Method |
Precise Learning Objective |
Linked |
Question / Activity
(Designed for maximum working out) |
Stepping Stones |
Pitstop Check
(Thinking Map) |
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Students to recall current composition of the earths atmosphere: about four-fifths (approximately 80 %) nitrogen, about one-fifth (approximately 20 %) oxygen and small proportions of various other gases, including carbon dioxide, water vapour and noble gases. |
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What is the composition of the earths atmosphere? Draw accurate pie charts for the composition of the atmosphere. |
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Students should be able to, given appropriate information, interpret
evidence and evaluate different theories about the Earth's early
atmosphere. |
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How has the Earths atmosphere evolved? Earths early atmosphere:
https://www.youtube.com/watch?v=Gyn754vw8ZQ |
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One theory suggests that during the first billion years of the Earth's
existence there was intense volcanic activity that released gases that
formed the early atmosphere and water vapour that condensed to
form the oceans. At the start of this period the Earth's atmosphere
may have been like the atmospheres of Mars and Venus today,
consisting of mainly carbon dioxide with little or no oxygen gas. |
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How has the Earths atmosphere evolved? Evolution of the Earth's atmosphere:
https://www.youtube.com/watch?v=gwGeH9O8Rx4 |
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Volcanoes also produced nitrogen which gradually built up in the
atmosphere and there may have been small proportions of methane
and ammonia.
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What types of gases did volcanoes produce? |
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When the oceans formed carbon dioxide dissolved in the water and
carbonates were precipitated producing sediments, reducing the
amount of carbon dioxide in the atmosphere. No knowledge of other
theories is required. |
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What happened to the atmopshere when the oceans formed? |
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Algae and plants produced the oxygen that is now in the atmosphere
by photosynthesis, which can be represented by the equation. |
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What process has caused oxygen levels in our atmosphere to increase since its formation? Demo: Aquatic plants (eg Elodea) producing oxygen in daylight.
(Interleaving opportunity to require practical with colours and ruler for intensity). |
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Algae first produced oxygen about 2.7 billion years ago and soon after
this oxygen appeared in the atmosphere. Over the next billion years
plants evolved and the percentage of oxygen gradually increased to a
level that enabled animals to evolve. |
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When did Algae first produce oxygen? |
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Algae and plants decreased the percentage of carbon dioxide in the atmosphere by photosynthesis. |
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How did Algae and plants affect the atmosphere? |
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Carbon dioxide was also decreased by the formation of sedimentary rocks and fossil fuels that contain carbon. |
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Apart from through the process of photosynthesis, what else has caused carbon dioxide levels in the atmosphere to decrease since its formation? |
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Students should be able to describe the main changes in the atmosphere over time and some of the likely causes of these changes |
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How did the Earth's atmosphere change over time? Why did these changes happen? 2 x Demos to show the reactions occurring in a volcano
EW: Describe the theory of the evolution of the Earth’s early atmosphere.
or
Explain why the composition of the atmosphere has changed over billions of years.
or
Compare the Earth’s atmosphere to that of Mars and Venus. |
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Students should be able to describe and explain the formation of deposits of limestone, coal, crude oil and natural gas. |
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How and why did limestone, coal, crude oil and natural gas form? |
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