Land, water, and how Earth changes (grade 2) · lesson

Fast and slow changes

💡 Some land changes are fast, like a volcano. Some are slow, like a canyon.

A volcano or a landslide can change land in minutes or days.

Wind and water wear rock away bit by bit. That is called erosion.

A river cuts a deep canyon over a very, very long time.

🧠 How to think about it

Could you watch it happen in one day? Then it is fast. Does it take longer than a life? Then it is slow.

🏡 Try it at home

Build a little hill of sand or dirt outside. Pour a cup of water slowly on top. Watch a tiny canyon form.

💡 Plants, walls, and rows of trees can slow wind and water from moving land.

Grass roots hold dirt in place. So rain washes less dirt away.

A row of tall trees slows the wind on a farm.

We can test ideas on model hills and compare what washes away.

🧠 How to think about it

Read the graph. The bare hill lost 8 cups. The grassy hill lost 2. Grass held the dirt best.

🏡 Try it at home

Make two dirt piles. Press leaves or grass on one. Pour water on both. Which loses less dirt?

💡 A map uses shapes and colors to show land and water from above.

On most maps, blue shows water.

A river is a long thin wavy line. A lake is a round blob.

An island is land with water all around it.

🧠 How to think about it

Look at the shape and the color. Blue and long and thin? A river. Land with blue all around? An island.

🏡 Try it at home

Draw a map of your room from above. Add a blue lake rug or a river if you like!

💡 Water is in oceans, lakes, rivers, and ice, and it can be solid or liquid.

Most of Earth's water is in the oceans.

Lakes and rivers hold liquid water.

Glaciers and snowy mountain tops hold frozen, solid water.

🧠 How to think about it

Is it cold enough to freeze? Then the water is solid ice. If not, it is liquid.

🏡 Try it at home

Put some water in a cup. Freeze half in the freezer. Compare the solid and the liquid.