Big or Small: Measure It All
Western Reserve Public Media

Video Supplements: Air
Balloon Design Challenge

Students design and make a hot air balloon using a plastic bag. They measure the time it stays in the air and its distance from the launch point.


Students will understand how to convert time and distance measurements.


Standards Addressed — Mathematics

Grade 5
Use Measurement Techniques and Tools, Benchmark B
05. Make conversions within the same measurement system while performing computations.





  1. Divide the students into groups of two or three.

  2. Have available various types of plastic bags, string and paper clips. Following are some guidelines:

    Dry-cleaning bags work the best because they are the lightest, but all types should work

    Students can use paper clips around the bottom to keep some balance

    Students should use string to tie off the top if they are using a dry-cleaning bag

  3. Have one or two people hold the bag while the other teammate blows hot air into the bottom using the hair dryer. The students should hold the bag until they feel a tug on the material. It is helpful to gather the bottom of the balloon so that the hot air remains in the balloon.

  4. Students should measure in seconds (and convert to minutes) the time from when they release the balloon until any part of it touches the ground. Students should further measure the distance from the launch site to the landing site in centimeters (and convert to meters).

  5. It is a good idea to do this activity outside (if electricity is available). Sometimes the balloons will go as high as the second story of a school. Indoors, the balloons can generally hit the ceiling.

  6. Extension: Older students can use a clinometer to determine the actual height that the balloon met. For instructions on making a clinometer, go to the School Yard Clinometer Web site at The string on the clinometer will show the tangent angle: Tan = Opposite/Adjacent.

  7. Science Connection: “When air or any other gas gets hot and expands, it gets less dense (lighter) because the same amount of air occupies a larger space. Hot air balloons fly because they contain warmer, lighter air. The air in the balloon, being warm, is less dense (lighter) than the cool air around it so it floats upward, like a cork in water. When the air gets cool, the balloon will sink again.” (Source: NASA)



Balloon Design Balloon is well-designed and constructed. Balloon flies well but has some problems. Balloon needs some design changes. Balloon didn’t fly.
Group Work Group worked very well together, with each person doing a part of the task. Group worked well together, but some members were not as involved as others. Group had some problems working together. Some members were not involved. Group was dysfunctional.
Measurement Both the time and distance measures, and their conversions, were accurate. Both the time and distance measures were accurate, but the conversion had an error. Either the time or distance measure was inaccurate. The conversion had an error. Measures were inaccurate.
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