1. Unit 11 Lesson 1 What Are the Oceans Like? Copyright © Houghton Mifflin Harcourt Publishing Company

2. Unit 11 Lesson 1 What Are the Oceans Like? Copyright © Houghton Mifflin Harcourt Publishing Company

3. Unit 11 Lesson 1 What Are the Oceans Like? That’s a Lot of Water! Copyright © Houghton Mifflin Harcourt Publishing Company

4. Unit 11 Lesson 1 What Are the Oceans Like? That’s a Lot of Water! Copyright © Houghton Mifflin Harcourt Publishing Company Five oceans separate and surround Earth’s landmasses. They are, from largest to smallest, the Pacific, Atlantic, Indian, Southern, and Arctic Oceans.

5. Unit 11 Lesson 1 What Are the Oceans Like? That’s a Lot of Water! Copyright © Houghton Mifflin Harcourt Publishing Company Oceans cover about 71% of Earth’s surface, almost three times the area that land covers.

6. Unit 11 Lesson 1 What Are the Oceans Like? That’s a Lot of Water! Copyright © Houghton Mifflin Harcourt Publishing Company

7. Unit 11 Lesson 1 What Are the Oceans Like? Same Ocean, Different Water Copyright © Houghton Mifflin Harcourt Publishing Company

8. Unit 11 Lesson 1 What Are the Oceans Like? Same Ocean, Different Water Copyright © Houghton Mifflin Harcourt Publishing Company

9. Unit 11 Lesson 1 What Are the Oceans Like? Same Ocean, Different Water Copyright © Houghton Mifflin Harcourt Publishing Company 1.Ocean water is salty, so you can’t drink it. The saltiness of water is its salinity.salinity Salinity makes water denser, so boats float more easily in the ocean than they do in fresh water. 2.Exploring beneath the ocean’s surface requires SCUBA tanks for air and suits to keep warm. 3.Water pressure is the force of water pressing against whatever it surrounds.

10. Unit 11 Lesson 1 What Are the Oceans Like? Same Ocean, Different Water Copyright © Houghton Mifflin Harcourt Publishing Company

11. Unit 11 Lesson 1 What Are the Oceans Like? Same Ocean, Different Water Copyright © Houghton Mifflin Harcourt Publishing Company At certain depths, a submersible—an underwater vehicle which provides air, light, and protection from water pressure and cold—must be used. Some places are too deep for human-driven submersibles, so robotic submersibles are used.

12. Unit 11 Lesson 1 What Are the Oceans Like? Same Ocean, Different Water Copyright © Houghton Mifflin Harcourt Publishing Company

13. Unit 11 Lesson 1 What Are the Oceans Like? Same Ocean, Different Water Copyright © Houghton Mifflin Harcourt Publishing Company

14. Unit 11 Lesson 1 What Are the Oceans Like? Is the Ocean Floor Flat? Copyright © Houghton Mifflin Harcourt Publishing Company The floors of all the world’s oceans share roughly the same features.

15. Unit 11 Lesson 1 What Are the Oceans Like? Is the Ocean Floor Flat? Copyright © Houghton Mifflin Harcourt Publishing Company

16. Unit 11 Lesson 1 What Are the Oceans Like? Is the Ocean Floor Flat? Copyright © Houghton Mifflin Harcourt Publishing Company

17. Unit 11 Lesson 1 What Are the Oceans Like? Is the Ocean Floor Flat? Copyright © Houghton Mifflin Harcourt Publishing Company

18. Unit 11 Lesson 1 What Are the Oceans Like? Is the Ocean Floor Flat? Copyright © Houghton Mifflin Harcourt Publishing Company

19. Unit 11 Lesson 1 What Are the Oceans Like? Islands Come and Go Copyright © Houghton Mifflin Harcourt Publishing Company 1.Oceanic trenches form where two plates meet and one sinks beneath the other, releasing magma at the boundary.

20. Unit 11 Lesson 1 What Are the Oceans Like? Islands Come and Go Copyright © Houghton Mifflin Harcourt Publishing Company 2.Volcanic island chains form at plate boundaries and grow until they poke into the air, creating volcanic islands. The islands weather and erode over time and eventually disappear beneath the water again.

21. Unit 11 Lesson 1 What Are the Oceans Like? Islands Come and Go Copyright © Houghton Mifflin Harcourt Publishing Company 3.In tropical regions, coral reefs form in shallow water around volcanic islands. These reefs can grow until they encircle an island. A reef can come out of the water, forming land that surrounds a lagoon of shallow water. 4.When a volcanic island sinks far enough to disappear, the ring-shaped coral, called an atoll, is left around the lagoon.

22. Unit 11 Lesson 1 What Are the Oceans Like? Islands Come and Go Copyright © Houghton Mifflin Harcourt Publishing Company

23. Unit 11 Lesson 1 What Are the Oceans Like? Islands Come and Go Copyright © Houghton Mifflin Harcourt Publishing Company

24. Unit 11 Lesson 1 What Are the Oceans Like? Copyright © Houghton Mifflin Harcourt Publishing Company

25. Unit 11 Lesson 1 What Are the Oceans Like? Copyright © Houghton Mifflin Harcourt Publishing Company