Theory of Flight 02 - Balloons 2


Compare the physics of density and weight in a buoy slowly filling up with water to a balloon slowly filling up with hot air (a sketch will be MOST helpful)


LEARNING GOAL FOR TODAY: I will be able to relate the principles of buoyancy to an articulate 12 year old after today's class.


Let's finish our conversations on a grading rubric for this project. Here's what I came up with... let's see what sort adjustments you suggest.

  • Teamwork (3 pts: 0 = none, 1 pt = minimal, 2 pts frequent, 3 pts constant)
  • Design/Creativity* (2 pts: 0 = stencil, 1 = some stencil, 2 no stencil)
  • Balloon Performance* (2 pts: 0 fail, 10 ft or less, above 10 ft)

All sentence/paragraph suggestions are MINIMUMs

  • Written Work:
    • Demonstrated understanding of Buoyancy (5 pts)
      • Explain why your balloon flew or failed to fly in terms of buoyancy (1 - 2 paragraphs)
      • What worked best in terms of your design (2 sentences)
      • What part of your design worked poorly (2 sentences)
    • Reflection (5 pts)
      • What was your role in this project (2 thoughtful sentences)
      • How well did you preform that role? (2 thoughtful sentences)
      • What would you personally do different next time? (2 thoughtful sentences)
      • What did you learn during this investigation? (2 thoughtful sentences)

17 pts total

* team score


Work with your group to design and sketch your balloon (you can't start building until you have a well-crafted sketch with labels).


  • Don't do anything stupid-- if you have to ask, then yes, you're doing something stupid
  • Everyone must use the same amount of paper
  • I have lots of regular ol' glue, hot glue is not allowed
  • Rigid structures such as struts and such are not allowed (they will only provide minimal stability and their weight is just not worth the effort)
  • Your goal is to achieve altitude, not necessarily flight time (in other words, if you catch an advantageous gust of wind, that won't help you much)


A spec of sand will fall when dropped. However, a much larger soap bubble will float on the air. We say that the soap bubble is buoyant. The spec of sand clearly is not.

What could we do to that spec of sand to make it buoyant (in otherwords, how could we make that spec of sand float on the air?).