Warm Air Rises to the Top

Contributor: Nichole Brooker. Lesson ID: 11843

Have you ever watched flames and smoke? What direction do they go? Why do you think that is? It's because warm air rises! Put on your scientist hat and try a fun (and safe) experiment with balloons!


Physical Science

learning style
personality style
Grade Level
Primary (K-2)
Lesson Type
Quick Query

Lesson Plan - Get It!

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  • Have you ever wondered why it was warmer on an upper floor of a house or apartment building?
  • Have you ever sat in a basement or ground floor room and were cold, but after going upstairs, you were warm?
  • How do you explain that?

cartoon boy with a thought bubble of a question mark

This is what happens to warm air! It rises, or goes up.

  • Why does warm air go up?

Warm air rises for the same reason oil sits on top of water when you pour them together. Oil is lighter than water, so it sits atop the water when the two are put in the same container.

Similarly, when air or any other gas is heated, it expands. When air expands, the molecules spread apart and become less dense or lighter than the air around them, so the air floats upward.

Hot air balloons are a great example of hot air rising.

  • Have you ever seen a hot air balloon in person?

A hot air balloon has a basket to carry the people, ropes to connect the basket to the balloon, and fire! When the fire heats the air inside the balloon, it makes it float into the sky!

  • Want to learn more about hot air balloons?

Watch this video!

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Print four copies of Draw and Describe How Hot Air Rises found in Downloadable Resources in the right-hand sidebar.

Draw a series of four pictures to explain how hot air balloons work on your four Draw and Describe How Hot Air Rises sheets.

Label the parts of your pictures. You will use these pictures in the next section.

  • Isn't it fascinating that the air we breathe can also make a hot air balloon float?

Science is so cool!

Continue to the Got It? section to review what you have learned before experimenting with how warm air takes up more space than cold air!

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