You and your students are going to show that air has weight, using balloons and a balance made with a yardstick.
Step 1: Get supplies.
Balloons
You will need at least 8 inflated balloons for this activity. Your students will work in pairs to blow up balloons. If that gives you more than 8 inflated balloon, that’s fine. You may want to run the experiment more than once.
For each balloon, you will need the following supplies:
- a latex balloon that is not inflated (All the balloons must be the same size & shape. We recommend buying a package like this one from Amazon. Mylar balloons will not work because they do not compress the air inside.
- a small binder clip (¾” wide) (available in office supply stores or on Amazon
Ribbon or string for measuring
After inflating a balloon, students will check the circumference of the balloon to make sure it is fully inflated. (This activity will only work if the balloons are fully inflated — which to most people looks like they are about to pop!) Students will measure the circumference with a ribbon or string that’s cut to the length of the circumference.
To figure out that length, check your balloon package for the size of your balloons. The size is the diameter of the inflated balloon. Find the circumference by multiplying the diameter by pi (3.14) or by checking the table below. Once you have the circumference, cut that length of string or ribbon for each pair of students.
Balloon diameter (from package) |
Circumference/Ribbon length |
12 inches |
36 inches |
11 inches |
34 inches |
5 inches |
15 inches |
Any other size |
diameter X 3.14 (round down) |
Balance Scale
To set up for this activity, you will need to make a balance scale. It’s easy. All you need is:
- Teacher Instructions for making the scale & balloon corral
- Yardstick
- 5 medium (1-¼ inch) binder clips like these
- 2 jumbo paperclips like these
- A wooden ruler
- Pencil
- Book
- A cleared off desk or desk
Balloon Corral (optional, but nice to have)
Having balloons loose in the classroom can distract students. We use a balloon corral to keep our balloons from roaming. To make one, you need:
- a coat hanger
- a book to serve as a weigh
- a few more jumbo paper clips
Step 2: Print student handouts & teacher instructions
Each student will need a copy of the Weight of Air handout. . If it's helpful, here is an Answer Key for teachers.
To make a balance scale and optional balloon corral, you will need to print out the Teacher Instructions
Step 3: Before class, make your balance scale.
If you have all your materials ready, this should take less than 20 minutes.