Grade 3 (age 8-9)

grade 3 Earth's Appearance

Earth's Surface and Structure

The Earth we live on is a round ball, and from space it looks blue because so much of it is ocean. About 71 percent of the surface is sea and only 29 percent is land with mountains, rivers, and plains. Inside are layers of crust, mantle, outer core, and inner core that grow hotter toward the center. Tap the buttons and the view switches between Earth from space and Earth inside.

What does Earth look like?

🌍 Features of Earth

①Earth is a round ball

②71% of surface is sea, 29% land

③From space it looks blue

④The interior has many layers

⑤Air (atmosphere) wraps the Earth

Earth's Surface

🏔️ Various Landforms

①Mountain: high-rising land

②River: a path where water flows

③Sea: vast deep salt water

④Plain: wide flat land

⑤Mountains, rivers, and plains are on the 29% land; the sea is 71%

Summary

Composition of Earth

Surface = Sea(71%) + Land(29%)

Earth is a planet with a lot of water

Internal Structure

Crust → Mantle → Outer Core → Inner Core

It gets hotter as you go deeper

🎯 Key Points

①Earth is round and mostly sea

②Crust-mantle-core inside

③Land has mountains, rivers, seas, plains

④Air (atmosphere) wraps the Earth

⑤Life exists thanks to water and air

Examples and Unit Test

Example 1

On the surface of the Earth, which is wider, the sea or the land, and about what percent is sea?

The surface of the Earth is made up of sea and land.

The sea is about 71% and land about 29%, so the sea is much wider than the land.

▸ The sea is wider (about 71%)

The surface of the Earth is 71% sea and 29% land, so there is more sea.

Example 2

List the inside of the Earth from the outside inward (crust, mantle, outer core, inner core).

The inside of the Earth has several layers, and it gets hotter toward the center.

From the outside inward, the order is crust → mantle → outer core → inner core.

▸ Crust → mantle → outer core → inner core

The inside of the Earth is crust, mantle, and core, getting hotter inward.

Unit-test style

Which statement about Earth is correct?

①On the surface, land is wider than the sea

②About 71% of the surface is sea

③The Earth is square-shaped

④The inside of the Earth is made of a single material

⑤The inside of the Earth gets colder toward the center

▸ ② About 71% of the surface is sea

The sea covers about 71% of the surface, much more than land (about 29%).

Sea is wider than land (①), the Earth is a round ball (③), the inside has several layers of crust, mantle, and core (④), and it gets hotter toward the center (⑤).

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Plant Life Cycle

Shadow and Sunlight