LEARN NC

4.4 Balloon flinkers

By Erin Denniston

Provided by Kenan Fellows Program.

three balloons in the sky

Students will try to determine how much weight a balloon gondola can carry while it “flinks” in the air for 20 seconds.

Learning outcomes

Students will know:

  • Whether an object floats or sinks depends not only on the properties of the object itself, but also on the properties of the fluid in which it is situated
  • Gravity is the downward force that pulls objects towards the earth
  • Buoyancy is the upward force of a fluid that pushes up on an object

Teacher planning

Time required

45–60 minute session

Materials needed

  • small items used in previous activities (magnet counters, paper clips, pennies, packing peanuts, etc)
  • helium balloons
  • egg carton
  • string
  • triple beam balances
  • pencils
  • scissors

Student handouts

Balloon flinkers data sheets
One per student
Open as PDF (19 KB, 3 pages; also available as Microsoft Word document)

Pre-activities

  1. Place supplies of the small items used in previous activities on central supply table. Label the table “PAYLOADS.”
  2. Get helium balloons the day of the activity. Many grocery stores will give teachers 10–15 balloons free of charge or they will charge a small fee. Another alternative is to buy a small tank of helium from Party City, Wal-Mart, or Target.
  3. If making your own helium balloons, add a ribbon about 4 feet long to each balloon.
  4. Cut a cardboard egg carton into 12 separate cups. Add a piece of string to each cup to make a small egg carton bucket. This “gondola” will carry the payloads for the balloon “flinker.”
  5. Attach a gondola to each of the helium balloons. Keep the balloons out of sight until the students are ready to go to work.
  6. For each group of students, provide a triple beam balance.
  7. For each pair of students, provide the pencils and scissors.
  8. Students will need their Floatless Boats and Measuring Weight data sheets from previous activities.

Activities

  1. Go over the results from the previous activities again. Talk about what floated and what sank. Hold up a few of the items that students identified as floaters and ask them what will happen if you dropped the item in water. Then, hold the item out in the air and ask what will happen if you dropped it in the air. Drop it. Ask why it did not float. Define the word fluid for students. Fluid is a substance that flows or moves and has no shape of its own. Liquids and gases are both fluids.
  2. Bring out a helium balloon. Ask students why the balloon is floating. Encourage the use of the words density, gravity, and buoyancy.
  3. State the engineering challenge: Students will try to determine how much weight the balloon gondola can carry while it “flinks” in the air for 20 seconds. To be a successful balloon “flinker,” no part of the balloon or the gondola can touch either the ceiling or the floor during the 20 seconds.
  4. Students will choose one type of payload at a time. They may use as much of the payload as they like but they cannot mix the payloads.
  5. Students will weigh the payload before adding it to their gondolas and record the data on the data sheet.
  6. After recording the weight, students will add the payload to the gondola and let the balloon go. They will record the results with an up or down arrow, indicating the direction the balloon headed when released.
  7. Allow plenty of time for experimentation while insisting that students measure and record results accurately.
  8. Discuss results with students. What was different in making things ‘flink’ in water versus making it ‘flink’ in the air? How were the forces of buoyancy and gravity working on the balloon? How does weight come into this? Tell students they are going to use their new knowledge to create a brand new toy.
  9. Have students create a new toy that “flinks.” They can actually make it or just draw/write about it. Then, have students draw or write an ad for the toy that shows how and why it works. Students should use terms from the word bank.

Assessment

Students will be assessed on the clarity of their flinking toy explanations and advertisements as well as the correct use of words from the word bank.
Review student data sheets for accuracy.

Supplemental information

For an interesting article relating to the difficulties children encounter with the concepts of floating, sinking and density, see the article “Challenges in Understanding Density” from the President and Fellows of Harvard College, Understandings of Consequence Project.

Critical vocabulary

equilibrium
a condition in which all forces acting on an object are canceled by others, resulting in a stable, balanced, or unchanging system
gravity
the force of attraction exerted by a celestial body, such as Earth, upon objects at or near its surface, tending to draw them toward the center of the body
buoyancy
the upward force that a fluid exerts on an object less dense than itself
weight
the measure of how much “pull” gravity has on a certain mass
density
the quantity of something per unit volume, unit area, or unit length
fluid
a substance that tends to flow and to conform to the outline of its container, a liquid or a gas
flink
a made up word for something that neither floats nor sinks in a fluid

North Carolina curriculum alignment

Science (2005)

Grade 1

  • Goal 3: The learner will make observations and conduct investigations to build an understanding of the properties and relationship of objects.
    • Objective 3.01: Describe the differences in the properties of solids and liquids.
    • Objective 3.03: Classify solids according to their properties:
      • Color.
      • Texture.
      • Shape (ability to roll or stack).
      • Ability to float or sink in water.
    • Objective 3.04: Determine the properties of liquids:
      • Color.
      • Ability to float or sink in water.
      • Tendency to flow.
  • Goal 4: The learner will make observations and conduct investigations to build an understanding of balance, motion and weighing of objects.
    • Objective 4.04: Observe and describe balance as a function of position and weight.
    • Objective 4.05: Describe and observe systems that are unstable and modify them to reach equilibrium.
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