Activity 3: Bag Balloons

Aim: Students will construct a model of Hot air Balloon and demonstrate that Heat changes air.

Material Required:

  • Plastic bag
  • Paper clips (used for weight)
  • Small pieces of paper or stickers (decorations)
  • String
  • One hair dryer (heat source)
  • Party balloons


  1. Decorate the plastic bag. Decorations should be small and light, such as small scraps of paper or stickers.
  2. Now, tie a string around the top of the plastic bag.
  3. Add paper clips evenly spaced around the bottom of the plastic bag.
  4. Now,Hold the plastic bag over the hair dryer (on the high setting) and let the plastic bag fill with hot air. 
  5. The plastic bag becomes buoyant as it fills with hot air.After this release the plastic bag. The hot air inside the balloon is lighter than the air outside and plastic bags begins to float.