Balloon On A Stick

Age

Elementary School, Middle School, High School

Format

Hands-on

Materials

   Round balloons (at least two for each time you do the demo)
   Wooden skewer
   Hand lotion 

Safety Precautions

Science Theatre demonstrators must keep the safety of themselves and their audience in mind at all times. All Science Theatre demonstrators must have read through the Safety Training page. The ST Safety Box with first aid kit, fire extinguisher, etc. should always be available to demonstrators. Always wear safety gloves, glasses, and a labcoat if handling chemicals; always perform potentially dangerous demonstrations at a safe distance from the audience; and always keep a very close eye on any volunteers you call from the audience. Skewers are sharp. Balloon pieces might fly through the air. Use general precaution.

Preparation

It’s best to blow up a bunch of balloons before the demonstration.

Demonstration

1. Put some hand lotion on the entire length of the wooden skewer (this just reduces the friction and allows the skewer to slide though the balloon.

2. Show the kids the sharp skewer, and the balloon. Ask them to hypothesize what will happen if you poke the balloon with the stick. (you may need to explain that hypothesize is a science word for “take your best guess”)

3. Pop the balloon by sticking the stick into it horizontally. (Hold the balloon at the bottom by the tie, insert stick perpendicular to the tie.) The balloon should pop.

4. Now take another balloon and show them the bottom. Is there anything different (there is a bump, it is darker in color, etc) What are balloons made of? (latex, a kind of rubber. Explain why the balloon is darker in that area. (the polymer is less stretched out, you can demonstrate the difference using an uninflated balloon, showing stretched and not stretched)

5. Have the kids guess again if you will be able to stick the skewer through the balloon, this time through the other side, where the rubber is darker and out through the side that has the tie on it.

6. Gently but firmly insert the skewer into the balloon. It takes a little bit of twisting and is a good idea to practice before you do the demo.

7. Ask the kids why it worked, and if they have any questions! This is science that you CAN do at home!

What to Say

Read through the #Demonstration. What to say is within.

Why It Is

Balloons are made of latex, a polymer made of molecule strands that are all tangled together (think spaghetti). Bonds between the strands, called cross-links give it its elastomeric properties. (You can stretch it to a certain point without breaking it.) The molecules on the sides of the balloon are already very stretched, and break much easier than those on the top or bottom of the balloon.

Real Life Examples

Elastomers are used for a variety of products, including balloons, bouncy balls, and rubberbands.