Checkpoint: fast air and storms

A strong wind blows fast over a weak roof. Why might the roof lift?

• The wind is heavy and pulls the roof up
• The air above is fast, so its pressure is lower than below
• The air above is fast, so its pressure is higher than below

You hear thunder while you play outside. Where should you go?

• Into a strong building
• Under a tall tree standing alone
• Onto the open ground and lie down

What makes the sound of thunder?

• Clouds bumping into each other
• Hot air expanding fast
• Rain hitting the ground