Land and Water

在B站看见了一个系列视频，据说是美国小学生的自然科学课，刚好拿来学一学英语。下面是做的一些笔记以及自己尝试的一些描述。
B站视频地址

The Earth has many different shapes.
There are many different kinds of land.
At the end of land, there are many cliffs. A cliff is a high, steep part of land.
A mountain is the highest kind of land. It is very steep. A hill is a high area of land; it is smaller than a mountain.
Valleys and plains are low lands. A valley is a low land between mountains. A plain is a flat area of land. There are not many trees on a plain.
A river is a large moving piece of water. A stream is a small river. Streams usually start at a mountain and finish at a beach.
A lake is a large area of water.

My description:
The Earth has many kinds of land and water.
A mountain is the highest land, it is very steep(the angle of size goes up very quickly) that is not easy to climb. Hills are lower than mountains but they are still high land. And hills are not steep.
A Valley is between mountains or hills. Canyons are steeper than valleys.
A plain is a flat land without many trees. If a farmer in the plain we will call it field.
Cliffs are high and steep, even vertical. They are sudden drop or rise in the land, and of course, they are dangerous.
An ocean is a kind of water land. It is a large area and full of salt water. Lakes are smaller than oceans, and they are full of fresh water.
Rivers and streams are moving water. A river is larger and deeper than a stream. We can boat on a river but can't on a stream.