Science project

Hot Air Balloon Heights




Elementary School, Fifth Grade

Difficulty of the Project



About $5

Safety Issues

This Project is relatively safe.

Time Taken to Complete the Project

2 Days


To find out if I made a hot air balloon with a toaster as a heat source and a bag for a balloon, would a bigger bag fly higher than a smaller bag?

Materials and Equipment

  • Toaster (Heat Source)
  • 4 Plastic Bags (Each with a different measurement. I cut each one a little smaller)
    • 73.6cm
    • 63.5cm
    • 43.18cm
    • 27.94cm
  • 1 Post Board, 55.8 x 71.1cm
  • Scotch Tape
  • Yarn
  • Sticky Pads
  • Scissors
  • Tape Measure
  • Push Pin
  • Pencil
  • Marker
  • Notepad


The first hot air balloon was invented in 1782 by two brothers, Joseph and Etienne Mongolfier. They discovered that hot air was lighter than cold air. They made a small silk balloon and it elevated thirty-two meters in the air. They found out that the hotter the air, the higher the balloon rose. They two brothers promised their dad they would never fly the machine themselves, so they sent a duck, a sheep and a chicken into the air. They flew for eight minutes and the animals were still alive. The entire science academy and Louis XVI witnessed the entire event. Louis XVI allowed a man named, Pilatre Rosier, to attempt to fly with a passenger. Their flight over Paris lasted 28 minutes while both men fed a fire placed in the middle of the basket.

The discovery gave the brothers a legacy of flying balloons. A competition started up between Pilatre and the brothers to see who could fly the highest. They started making balloons bigger. Pilatre died after he tried to fly from France to England in 1785. His balloon caught fire because he had a small bag of hydrogen attached to his basket.

Research Question

When making your own hot air balloon, does a bigger bag cause the balloon to fly higher than a smaller bag?


My guess is, the bigger the hot air balloon, the higher the balloon will go.

Experimental Procedure

  1. I put a piece of tape on a piece of yarn and placed the push pin into the tape and had my dad get on a ladder and put the push pin into the highest point in our ceiling, so the yarn was hanging from the ceiling.
  2. I taped the end of the yarn to the floor and marked one meter increments all the way up the yarn with a piece of tape.
  3. I cut the poster board in half and taped it together to form a circular shape, making sure it fit tightly around the toaster.
  4. I cut a little bit off of each bad except one. The first bag, I cut about 10 cm off, the second 30cm off, and the third about 45 cm off.
  5. I plugged the toaster into the wall by the measured yarn.
  6. Finally, I was ready to complete the experiment. I tested each size bag, placing each bag over the circular poster board.
  7. Turned the toaster on (each time at the same setting in order to have just one variable).
  8. Placed the poster board with the bag attached over the toaster. Held each bag up in place, so it didn't melt.
  9. Waited for the bag to fill. Once filled, if the bag didn't go up straight, I placed sticky notes for weights on the end of the bag and tried it again until each bag went up straight 3 times each.
  10. I recorded what happened on a notepad.


I tested the bigger bag first and each time it rose almost to the top of my ceiling (about 3 meters) as the bags got smaller, they didn't rise as high as the first bigger bag, the smaller the bag the less it rose.

73.6 CM
63.5 CM
43.18 CM
27.94 CM

This graph below shows what happened with each balloon (bag) at each test.


In conclusion my hypothesis was correct. When i tested the biggest bag with the toaster as the heat source it rose the highest. Each time we tested a smaller bag it did not elevate as high as the first biggest bag. Next time, I would like to test what would happen if we changed the setting on the toaster to a higher degree or test different heat sources to see which bag would stay in the air the longest.


  • "All About Hot Air Balloons" 2006-2011
  • Bilbrey, Jim. Interviewed by Joshua Mora. Wildomar, CA: February 4, 2011
  • Bristow, David l. The Sky Sailors: True Stories of the Balloon Era New York, New York Farrar Straus Giroux 2010
  • Coombs, Charles Hot Air Ballooning New York, W. Marrow 1981
  • Genevieve Thiers "The History of the Hot Air Balloon" 2002
  • Kenneth Lafferty Hess Family "Free Science Project Ideas, Answers and Tools for Serious Students" 1-17-11 
  • Priceman, Marjorie Hot Air New York, New York Atheneum Books for Young Readers 2005

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Warning is hereby given that not all Project Ideas are appropriate for all individuals or in all circumstances. Implementation of any Science Project Idea should be undertaken only in appropriate settings and with appropriate parental or other supervision. Reading and following the safety precautions of all materials used in a project is the sole responsibility of each individual. For further information, consult your state's handbook of Science Safety.

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