Flatten an Index Card

Challenge your students (or family members or friends or anyone else you encounter) to find two ways to flatten an index card, without touching it.

To prepare, fold an index card in half and set it on the table to make a tent. 

Your challengee will likely immediately blow on the top of the card to push the middle down.

The challenge comes in finding a second way to accomplish the task. 

It's time to put your knowledge of Bernoulli and air pressure to work!  By blowing under the card, you'll move those air molecules out of the way, allowing the air molecules on top of the card to push the card down.

Air Pressure and Bernoulli:Clanging Cans

This demonstration is very similar to the balloons and the cardboard tubes.

There are two ways to try this one:

Version 1:
First, lay two empty soda cans on their sides a few inches apart, parallel to one another.

Blow between the cans and watch them roll together.  It happens because you've pushed the air molecules that were between the cans out of the way, so the air pushing on the opposite sides of the cans is unbalanced and the roll together.

Version 2:
Set up a bunch of straight straws parallel to one another, about half an inch apart from one another. 

Set the two cans upright on the straws, a few inches apart.

Blow between the cans and watch!

Summer Science Camp: Air Pressure Demonstrations

If your budget or location doesn't provide you with the opportunity to do a Chemistry Magic Show, consider a series of air pressure demonstrations.  They can be just as much fun, and the science behind them is easier for younger students to understand than the chemistry. 

Start things with a bang - literally - and use air pressure to crush a can. 

It follows nicely to collapse a milk jug. 

Set up the Balloon in a Flask and have students keep an eye on that while you're proceeding through other demonstrations. 

Sucking an egg into a flask is always a favorite.  A simple Internet search will provide you with instructions thousands of times over. 

Challenge a student to Blow up a Balloon in a Bottle! 

Give your students a shower with the Straw Fountain. 

Find two strong students to try to pull apart Two Plungers. 

Bernoulli demonstrations are a bit counter-intuitive and fun.  Try the cardboard tubes or balloons. 
And, if at all possible, finish with some bell jar demonstrations.

Air Pressure and Bernoulli: Rising Paper

This simple activity is a great introduction to Bernoulli. 

Cut strips of paper, about 1 cm wide.

Hold a single strip up to your lip. 

What do you think will happen if you blow across the paper?  How will the paper move? 

Many students will think that blowing across the paper will push it down.  In fact, just the opposite happens:

By blowing, you push the air molecules above the paper out of the way, so the air molecules located below the paper are unbalanced and push the paper up. 

Bernoulli: Ball in a Cup

Challenge your students to get the ping pong ball out of the cup* following this 1 rule:
     ~~They cannot touch the cup or ball with any part of their body.~~

The only way I know of to complete this task is to apply Bernoulli's Principle by blowing across the top of the cup and ball, allowing the ball to rise.

If that's too easy, you can add a second step to the challenge and have the students move the ball from one cup to another without touching anything.


*Try out the cup you plan to use ahead of time.  If the cup is too deep, it won't work.  If you use a paper cup, you can always cut the sides down.  But, be careful, if the cup is too shallow, students will just blow the ball out and not put Bernoulli to use.  I found that a cordial glass (see below for a cordial glass story) works well, if you have one shaped like mine!


Here's the story... when we were little (like, before we started school), my cousins, brother and I drank apple juice out of mini wine glasses at my Grandma's on special occasions, like Easter.  I was in college before I realized that those glasses were not in fact miniature wine glasses made for small children to use when the grown ups were drinking wine, but were really cordial glasses.  :)  Who knew?!?!

Air Pressure and Bernoulli: Balloons!

Hang two balloons so they are a few inches from one another.

Blow through the gap in the middle of the balloons.

The balloons move together!  You pushed the air molecules from the middle out of the way, allowing the air on the other side of the balloons to push them toward the middle.

Air Pressure and Bernoulli: Cardboard Tubes

Place two cardboard tubes (make sure they're nice and round) on a table, an inch or two apart from each other.

Use a straw to blow through the gap between the tubes.

The tubes roll together! You pushed the air molecules from the middle out of the way, allowing the air on the other side of the tubes to push them toward the middle.