Choose the sheet for the learner's age. Each prints on a single page. Build the project first, then fill it in together.
Ages 5-7: Draw & tell
Name: ______________________Date: ____________
Homemade Science with Bruce Yeany · Balloon in a Bottle · Ages 5-7
The balloon in the bottle
Look closely at your bottle and draw what you see.
1. Draw your bottle with the balloon blown up inside it. Draw both straws.
2. Is the bottle empty before you put the balloon in?
◯ Yes, nothing is inside◯ No, it is full of air
3. You covered the open straw with your finger and blew. What happened?
◯ The balloon grew big◯ The balloon stayed small
4. Draw an arrow showing which way the air went out of the bottle when the balloon grew.
5. What was the most surprising part?
Ages 8-10: Predict, test & record
Name: ______________________Date: ____________
Homemade Science with Bruce Yeany · Balloon in a Bottle · Ages 8-10
Predict, test, record
Test your balloon bottle and find out what the open straw does.
1. Predict: if you cover the open straw and blow into the balloon straw, the balloon will...
◯ grow as big as before◯ grow a little◯ not grow at all
2. Try each test and record what the balloon did.
Test
What I did with the open straw
What the balloon did
3. What did you find out about the open straw?
4. When you sucked on the open straw, what pushed air into the balloon?
◯ Your mouth pulled it in◯ The air outside pushed it in◯ The clay pushed it in
5. Why do you think the balloon stays big when you cover the open straw, even though the balloon's straw is open?
Ages 11-14: Explain & design your own test
Name: ______________________Date: ____________
Homemade Science with Bruce Yeany · Balloon in a Bottle · Ages 11-14
Explain the pressure
Use what you know about air pressure to explain and extend the experiment.
1. Use the words "compress" and "air pressure" to explain why a balloon can barely be blown up inside a sealed bottle.
2. Explain how sucking on the open straw inflates the balloon. What is really doing the pushing?
3. Boyle's law says that if you squeeze trapped air into half the space, its pressure...
◯ halves◯ stays the same◯ doubles
4. Design a fair test of one of Bruce's no-holes challenge solutions. Fill in your plan.
What I will change
What I will measure
What I will keep the same
5. Bruce's self-sealing balloon used wet oatmeal. Why did wet oatmeal seal the hole when dry oatmeal didn't?
6. Where else do you see air pressure doing the pushing? Give one real-world example.
Answer guide for grown-ups
Homemade Science with Bruce Yeany · Balloon in a Bottle · Answer guide
Answer guide
Ages 5-7: The balloon in the bottle
Open answer: look for effort and careful observation.
No, it is full of air.
The balloon stayed small.
The arrow points from inside the bottle up and out through the open straw.
Open answer: look for effort and careful observation.
Ages 8-10: Predict, test, record
Any prediction is fine. Result: it grows only a little, because the trapped air has nowhere to go.
Open answer: look for effort and careful observation.
It lets the bottle's air escape as the balloon grows. When it is covered, the balloon can hardly grow.
The air outside pushed it in.
When the balloon tries to shrink, it makes more room for the trapped air around it, so that air pushes less. The outside air pushing in through the balloon's straw is stronger, so the balloon stays big.
Ages 11-14: Explain the pressure
The bottle is already full of air. The balloon can only grow by compressing that trapped air, which raises its air pressure. Your lungs can't push hard enough to overcome it, so the balloon barely grows.
Sucking removes air from the bottle and lowers the pressure around the balloon. Atmospheric pressure outside is now higher, so outside air is pushed into the balloon through its straw. The atmosphere does the pushing, not the suction.
doubles
Example: change the method (straw and rubber band vs bypass straw); measure how full the bottle gets (for example, how far down the balloon reaches); keep the same bottle, balloon type and person blowing.
In water, oatmeal's soluble fiber forms a sticky gel, and the insoluble fibers bind it together into a plug. Dry powder has no gel to stick and seal.
Examples: drinking through a straw, a suction cup, a dented water bottle after a flight, a vacuum-sealed jar lid, a medicine dropper.