It may sound like it can't happen, but have your children learn about centrifugal force and watch an ounce lift a pound.
What You'll Need:
How to Watch an Ounce Lift a Pound:
Step 1: Have your children thread a five-foot piece of fishing line through an empty cotton spool. At one end, they should securely fasten the 1-oz object so that it can be whirled about without danger. Then have them fasten a 1-lb rock to the other end of the fishing line.
Step 2: Have your kids grip the spool so that they are also holding the string beneath it. Let the heavy rock dangle down about ten inches. Rotate the light object in a horizontal circle above their head.
Step 3: When the light object is spinning around fast, your children can release their grip on the string below the spool. As they continue to spin the light object, they will see the heavy object begin to rise on the string that goes through the spool. (Make sure they use a strong line and fasten objects securely so that the objects don't fly off.)
For more super science projects for kids, check out:
ABOUT THE PROJECT DESIGNERS
Swing on a Pendulum by Maria Birmingham, Karen E. Bledsoe and Kelly Milner Halls