We suggest students work in pairs for the first part of the activity. Homeschool students can work on their own, but you will need a minimum of eight balloons for this activity to work. The supplies calculated above will provide one balloon per pair of students. If that gives you more than 8 balloons, that’s fine. You and your students can run the experiment multiple times.

Prepare the String for Measuring

This activity will only work if the balloons are fully inflated — which to most people looks like they are about to pop! After inflating a balloon, students will measure the circumference of their balloon to make sure it is fully inflated. In order to do this, students need a piece of string (or ribbon) that’s cut to the length of the balloon’s 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 for each pair of students.

Make a Balance Scale Before Class

This will take about 20 minutes. You need a cleared off desk or table to set up your balance scale. You also need a yardstick, 5 medium binder clips, 2 jumbo paper clips, a wooden ruler, a pencil, and a heavy book. Follow the directions on the Teacher Instructions to make your balance scale.

Make a Balloon Corral (Optional)

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 heavy book, and a few more jumbo paper clips. Directions on how to make a balloon corral are found on the Teacher Instructions printout.

Organize Supplies for Distribution

In addition to the supplies used to make the Balance Scale and Balloon Corral, each pair of students will need the following materials.