Lesson Purpose
Scientists estimate that the Earth formed about 4.56 billion years ago. The Earth that we know today, the relatively peaceful home of myriad forms of life, didn't appear overnight. Rather, it took billions of years to slowly evolve into its current form. The process of accretion that led to the formation of the Earth was a violent one, and it produced an Earth that was only a little less violent and hostile. For a few hundred million years, the early Earth was characterised by high temperatures, toxic gases, high levels of radiation, and ongoing high-impact collisions. Over time, these conditions improved and the Earth took on its distinctive structure with differentiated layers of core, mantle, crust, and atmosphere. This distinctive structure has important consequences: First, it helps explain why the surface of the Earth changes over time; and second, it helps explain why the Earth evolved into a suitable setting for living things.
The outcomes of this lesson are: 1.) To explain how the Earth formed and the environment changed over time; 2.) To explain how the Earth's atmosphere formed.
The outcomes of this lesson are: 1.) To explain how the Earth formed and the environment changed over time; 2.) To explain how the Earth's atmosphere formed.
Activity 1 - It's Alive! The Universe Verse Book 2
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Activity Purpose
In Lesson 1.2, you read part of The Universe Verse, a comic book that illustrates many of the key elements of the Big History story. This second book tells the story of the formation of planet Earth and the emergence of life. This activity invites you to review the comic to get a very quick understanding of how the Earth was formed before moving on to the rest of the lesson. Activity Tasks
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Activity 2 - What was young Earth like?
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Activity Purpose
This video explains what life was like on the early Earth and asks us to think about what it would have been like to live on the Earth back then. It wasn’t pleasant, and it highlights the challenges emerging life forms had to overcome to survive. This video also previews the idea of plate tectonics, which will be the focus of the next two lessons in this unit. Understanding both the history of the Earth and plate tectonics are critical to understanding how the Earth became a place that could support life. Activity Tasks
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The layers of the Earth were – and still are – constantly moving, and it was this movement that resulted in the creation of separate continents. Life on each of the continents evolved independently until the continents were reunited much, much later in our story.
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Activity 3 - The Early Atmosphere
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The atmosphere of the Earth keeps changing and adapting to the conditions around it. There is a never-ending cycle of warming, cooling, and recovery from traumatic events.
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Activity Objectives
The atmosphere, like the Earth, has evolved over time. These changes in the atmosphere can be traced to changes on Earth. Many factors can influence the climate, but geological forces such as increased volcanic activity, and biological changes such as the development of photosynthesis, are two examples. It’s important to understand that the atmosphere is part of a larger system, and changes in that system can bring about changes in the atmosphere. Activity Tasks
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Activity 4 - Evaluating Writing
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Activity Objectives
You will be evaluating “Early Earth,” a sample Big History essay, using the rubric that will be used to grade your own writing in the course. The goal of this activity is to familiarize you with the rubric by asking you to review the rubric’s categories and the descriptions of the standards by applying them to a sample paper. Activity Tasks
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Activity 5 - The Driving Question Notebook
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Activity Objectives
By now, you should be familiar with the DQ Notebook activity. Although you won’t have much background to inform your work yet, it’s important that you begin to think about what you already know about this unit’s driving question. Activity Tasks
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Challenge Yourself! - Optional Activities
1. The Hadean was Earth's first geologic eon and lasted from 4.5 to 4 billion years ago. Named for the Greek god Hades, ruler of the underworld, it was a hellish and extremely violent time in our planet's early history.
2. Panthalassa is the name for the vast global ocean that surrounded the supercontinent Pangaea. It means "all" and "ocean" in a Greek.
3. Earth's early atmosphere was a noxious mix of hydrogen and helium, methane and ammonia. Today's atmosphere is a friendly-to-us mix of nitrogen, oxygen, and argon with traces of carbon dioxide, neon, and helium.
4. Ever noticed rocks with thin layers of red running through? It's probably a banded iron formation, a result of the Great Oxygenation Event that occurred 2.4 billion years ago.
2. Panthalassa is the name for the vast global ocean that surrounded the supercontinent Pangaea. It means "all" and "ocean" in a Greek.
3. Earth's early atmosphere was a noxious mix of hydrogen and helium, methane and ammonia. Today's atmosphere is a friendly-to-us mix of nitrogen, oxygen, and argon with traces of carbon dioxide, neon, and helium.
4. Ever noticed rocks with thin layers of red running through? It's probably a banded iron formation, a result of the Great Oxygenation Event that occurred 2.4 billion years ago.