seegongsik
Grade 2 (age 7-8)

grade 2 Air & Wind

Air is all around us even though we cannot see it. Air in a plastic bag makes it puff up, and when you fan yourself you feel air on your face; air moving from place to place is what we call wind. When the Sun warms the ground unevenly, the air over the warm places rises, and cooler air from around pushes in sideways to fill its place, which makes the wind blow. Change the wind strength in the picture to see how far the tree bends, how the pinwheel turns and when leaves start to fly.

What happens when the wind blows?

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🌬️ How things change with the wind
①With no wind the tree stands straight
②The stronger the wind, the more the tree bends with it
③The pinwheel turns, and once the wind is fairly strong, leaves come loose and fly
④We cannot see wind itself, but we can tell how strong it is from the things it moves

Air you cannot see

💨 Signs that air is there
①Swish an empty plastic bag through the air and close it, and it puffs up
②Fan yourself and you feel air touching your face
③Push an empty cup upside down into water, and the air inside keeps the water from filling it
🎈 Air has weight
①Hang the same balloon on each side of a balance and blow up only one: that side dips a little
②Air is light, but it has weight and takes up space
③When a lot of air moves very fast, as in a typhoon, it is strong enough to knock trees down

How does wind form?

🌡️ Warm air and cold air
①Warmed air spreads out, so the same amount of space holds less of it, and it rises
②Cold air is heavier and sinks
③Cooler air from around pushes in sideways to fill the place of the rising warm air, and that movement is the wind
④In the daytime land warms faster than the sea, so at the seaside the wind blows from the sea toward the land

Summary

🎯 Air and wind in short
①Air is all around us even though we cannot see it, and it has weight
②Wind is air moving from place to place
③Wind forms as warm air rises and cooler air pushes in to take its place
④Wind strength is described as a light breeze, a gentle wind, a strong wind or a very strong wind; a tropical storm with very strong winds is called a typhoon
⑤Without air we could not breathe

Examples and Unit Test

Example 1
What is wind, and how do warm air and cold air move?
1
Wind is air moving from place to place.
2
Warm air is light and rises, and cooler air pushes in sideways to take its place.
▸ Wind is moving air / warm air rises and cooler air fills its place
When air moves, we feel it as wind.
Example 2
We cannot see air. How can we tell it is there?
1
Trap air in a plastic bag and close it, and the bag puffs up.
2
Fan yourself and the moving air blows on your face.
▸ A puffed-up plastic bag and the breeze from a fan show that air is there
Air cannot be seen, but it fills the space all around us.
Unit Test
Which is the right reason the wind blows?
①Because air moves
②Because air disappears
③Because the ground shakes
④Because the Sun moves
⑤Because water flows
▸ ① Because air moves
1
Wind is air moving from place to place.
2
As warm air rises and cooler air pushes in to take its place, the air moves and the wind blows.
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