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How Do Hot Air Balloons Work?

Science For Kids

Up, Up, And Away!

Watching a hot air balloon take flight is a captivating sight. I have always appreciated its graceful lift-off and whimsical flight pattern. Floating along in our homeschool studies, the idea came upon me to include these remarkable modes of transportation as a thematic unit. A whole week dedicated to these seemingly magical balloons had my burners fueled! I was setting to take our learning up and away with all the science concepts rising up before me.

*Take off into the complete Hot Air Balloon Unit, full of learning activities, games, and paired worksheets HERE!*

The Amazing Molecule!

Right away, my kiddos knew that the balloon floated because they had already experienced the fact that hot air rises. I knew it was time to take this concept further, and expand their understanding of just why it is that heat rises, and likewise, how those magical balloons take flight.

If your young scientists are ready to turn up their learning burners, here's some helpful information to help learning soar!

*Grab the Molecule Making Activity Sheet Set HERE!*

Hot Air Balloon Unit: Molecule Making Activity
Follow the activity sheets to further understanding of molecules, atoms, and make three molecules! Five sheet set.

Hot Air Balloon Unit: Molecule Making Activity

Hot Air Balloon Unit: Molecule Making Activity

How Hot Air Balloons Work.

It's the amazing air molecules that give the balloon its capability. Not just any air molecules though, as the name implies, it has to be hot air molecules.


While we all can recognize that hot air rises, it's the properties of the hot air molecules that really need to be examined. When air molecules heat up, they expand, and not only do they expand, they bounce and move around. When the air molecules heat up inside the balloon and grow in size, the quantity of air molecules that can fit inside reduces, making the air inside the balloon less dense, or lighter, than the outside cool air molecules. Since cool air molecules are heavier, or more dense, the warm air molecules (and the envelope they are trapped inside) begin to float.


Once the pilot is ready to descend, she must open the cooling vent on the balloon, which then allows the hot air to escape. The cooler, heavier air then enters from the bottom. The cool molecules add weight, allowing the balloon to sink, and eventually land.


Hot Air Balloon Unit: Why Does It Work?
Illustration of air molecules in a hot air balloon

There's wondrous learning that comes from adventuring!



Find unique and engaging lesson plans HERE.


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