Experiment 2: 

"The Hovering Card Trick"

In 1737, Daniel Bernoulli discovered that moving air has less pushing power than still air.

You Will Need:

A Thread Spool

An 8 cm square of Cardboard

1 Thumbtack

Step 1:  Draw diagonal lines from corner to corner on the square.  The center of your "X" is the center of the cardboard square.

Step 2:  Carefully push the thumbtack through the center of the card, making sure the point of your thumbtack is away from fingers.

Step 3:  Hold the square under the thread spool so that the thumbtack is in the hole of the spool.

Step 4:  Lift the card and the thread spool.  Blow hard down the hole of the spool.  Take your hand away.  Can you blow the card off the end of the spool?

The Science Fact: 

The stream of air you blow down the spool passes between the spool and your square.  This moving air has less "pushing power" the the room air just below the card.  Since the push from the room air against the bottom of the card is stronger than the pushing power of the air you blew through the hole of the spool, the square is pushed up against the spool rather than away from the spool.