This is a very fun experiment that teaches children about air; its volume, density and pressure, without them even being aware of it. All you really need is a good set of lungs, some space and a few charts to document the races.
• Air Travel
• Air Movement
• Air Currents
1. Bring out the materials for your experiment and talk to the children about what you are going to be doing.
2. Talk about air and air pressure. Before you start the actual experiment, explore the balloons by inflating and deflating them. Allow the children a chance to feel the air moving out of the balloon. Discuss it.
3. Using two straws, slide them onto two separate pieces of string. Make sure they can slide without any difficulty.
4. Attach the ends of the string across an area. The best is between two trees but if you are doing it inside, just secure it to two walls.
5. Blow up a balloon and tape it to the straw, with the opening facing the wall that you are closest too.
6. Ask the children to predict what will happen. Have someone document it.
7. Let go of the balloon. It should move the straw down the string.
8. Set up races. Blow up balloons to different levels and have the children predict which balloon will win.
Questions to ask:
Why do you think the balloon inflates?
Where do you think the air goes when it deflates?
What do you think would happen if we fill up a balloon and let it go?
What do you think will happen if we attach the balloon to the straw?
Why do you think the straw is moving?
Would it move the straw if the straw wasn’t on the string?
Which balloon do you think will win?
Things to do:
Document predictions that the children make and the final outcome of the experiment.
Have the children document the experiment themselves with drawings or models. Show them how to use arrows to show air currents.
Keep a chart on what balloon one, if it was inflated a lot or a little.
A great way to expand on this experiment is to use different shaped balloons. Does a long and skinny balloon deflate faster than a round balloon? Another way to expand is to tape a weight onto the balloon to see if it slows down the speed of the straw.
I recommend that you make the string longer than what is in this video clip.