• Just your body! 

Procedure:

• Lift one arm straight up over your head
• Make sure to keep your other arm down at your side.
• Leave your arm up for one full minute.
• Look at your hands, which hand has more of a reddish tone?

What Happened?

 Blood was still being pumped throughout your entire body but gravity was working against you, especially on your hand over your head. It made it much harder for your heart to pump blood to this hand. Therefore the hand that remained at your side should have a reddish tone while the hand you kept in the air will not. 

Be sure to check out:

Your Pump: The Heart
More Heart and Circulatory System
Find Your Heart Word Search
Anatomy Links