seegongsik
Grade 3 (age 8-9)

grade 3 Earth's Appearance

Earth's Surface and Structure

The Earth we live on is shaped like a round ball, and from space it looks blue because its oceans are so wide. About 71% of the Earth's surface is ocean and about 29% is land, and on the land lie mountains, rivers and wide plains. Inside, the Earth is made of layers: from the outside in, the crust, mantle, outer core and inner core, and it gets hotter the deeper you go. Use the buttons in the first picture to switch between the Earth seen from space and its inside, and see the land and sea features in the second.

What is the Earth like?

🌍 Features of the Earth
①The Earth is shaped like a round ball
②About 71% of its surface is ocean and about 29% is land, so it looks blue from space
③Inside, it is divided into the crust, mantle, outer core and inner core
④The outermost crust is as thin as an apple's skin compared with the whole Earth; the picture draws it thicker so you can see it
⑤A layer of air (the atmosphere) surrounds the Earth

The Earth's surface

🏔️ Kinds of landforms
①Mountains: places where the land rises high
②Rivers: paths along which water flows from high ground to low ground
③The sea: wide and deep, filled with salt water
④Plains: wide, flat land with many fields and towns
⑤Mountains, rivers and plains are all on the land, which is about 29% of the Earth's surface

Summary

What the surface is made of
Earth's surface = ocean (71%) + land (29%)
The Earth is a planet with a great deal of water
Inside the Earth
Crust → Mantle → Outer core → Inner core
It gets hotter from the outside toward the center
🎯 Key points
①The Earth is round, and it has more ocean than land
②Inside, it is divided into the crust, mantle, outer core and inner core
③The surface has many landforms, such as mountains, rivers, seas and plains
④Air (the atmosphere) surrounds the Earth
⑤Thanks to water and air, living things can live here

Examples and Unit Test

Example 1
On the Earth's surface, which is larger, ocean or land, and about what percentage is ocean?
1
The Earth's surface is made up of ocean and land.
2
About 71% is ocean and about 29% is land, so the ocean is much larger.
▸ The ocean is larger (about 71%)
The ocean is more than twice as large as the land.
Example 2
List the inside of the Earth from the outside in: crust, mantle, outer core, inner core.
1
The inside of the Earth is made of layers, and it gets hotter the deeper you go.
2
From the outside in: crust → mantle → outer core → inner core.
▸ Crust → mantle → outer core → inner core
Press the inside button in the picture to see the four layers nested from the outside in.
Unit-test style
Which statement about the Earth is correct?
①The Earth's surface has more land than ocean
②About 71% of the Earth's surface is ocean
③The Earth is shaped like a square
④The inside of the Earth is a single layer
⑤The inside of the Earth gets colder toward the center
▸ ② About 71% of the Earth's surface is ocean
1
About 71% of the Earth's surface is ocean, much more than the land (about 29%).
2
The ocean is larger than the land (①), the Earth is a round ball (③), its inside is divided into the crust, mantle, outer core and inner core (④), and it gets hotter toward the center (⑤).
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Shadow and Sunlight

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