Earth: The Blue Planet

Lesson 4.1

An ocean is a large body of salt water.

1. What is an ocean?

Lesson 4.1

Lesson 4.1

2. About what percent of Earth is covered by oceans?

About 70% of Earth’s surface is covered by oceans.

3. What are three uses of the oceans by people?

1) Oceans are used for its living natural resources, such as fish, lobsters, and seaweed.

Lesson 4.1

2) Resources beneath the ocean floor, such as oil and natural gas, are extracted.

3) People also use the ocean for recreation and transportation.

4. Name the four oceans.

The four oceans are the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, and the Arctic Ocean.

Lesson 4.1

Lesson 4.1

5. Describe the Pacific Ocean.

The Pacific Ocean is the largest ocean and covers about 28% of Earth’s surface. It has the deepest area below sea level near the Philippine Islands.

6. Describe the Atlantic Ocean’s location and size.

The Atlantic Ocean is half the size of the Pacific Ocean. It lies between the Americas on its west side and Europe and Asia on its east side.

Lesson 4.1

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Lesson 4.1

7. What is fresh water?

Fresh water is water that has little or no dissolved salts.

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8. What are three ways that salts get into the oceans?

1) Rivers carry salts from dirt and rocks and carry it to the oceans.2) Waves pounding on shores pick up salts from rocks and sand, adding more salt into the oceans.3) Volcanoes erupting under the oceans add more salts to the oceans.

Lesson 4.1

9. What is evaporation?

Evaporation is the process of liquid turning into a gas.

Lesson 4.1

Lesson 4.1

10. What causes evaporation on the oceans?

Sunlight shines on the surface of the oceans, heating the water, and turning it into a gas called water vapor. Water vapor is an invisible, colorless, odorless, and tasteless gas.

11. What happens to the salt in water during ocean evaporation?

When water evaporates from the ocean, the salt remains behind.

Lesson 4.1

Lesson 4.1

12. What is the percent of the concentration of salt in the ocean?

The concentration of salt in ocean water is about 3.5 percent.

13. Why is most of Earth’s fresh water unavailable?

It is frozen and far away from the places where it is needed. Most of the frozen water is in the polar ice caps, Greenland, and in glaciers.

Lesson 4.1

Lesson 4.1

14. Where is freshwater found in Earth’s surface?

1) Seventy-eight percent of fresh water on Earth’s surface is frozen. Most of that is in ice sheets in Antarctica and Greenland, ranging up to 2.5 miles deep. Some other fresh water is frozen in glaciers, large bodies of ice that move slowly over land.

2) Twenty-one percent of the fresh water is liquid, most of this in rivers and lakes.

3) Much of the remaining one percent is in the atmosphere.

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The End