Try these experiments and observe what happens. Guess why it happens and compare your results to the answers below. You can also encourage your students to try NEWTON'S APPLE experiments at home.
On a rainy or stormy day, flip an empty soda bottle upside down into a glass measuring cup that has a spout and contains some colored water. The bottle must fit snugly in the measuring cup so that the lip of the bottle will not touch the bottom of the cup. Make sure that the water in the cup extends into the neck of the bottle. Mark a line on the cup to indicate the water level within the bottle. When the weather turns sunny, reexamine the water level within the bottle. Did it change? Why?
Use a rubber band to secure a metal spoon to the midpoint of a 2' string. Wrap the ends of the string around your index fingers. Rest your index fingers in your ears. Rock your body so that the spoon taps against the side of a table. What do you hear?
Trace the following fish shape (download the GIF file) on a piece of paper and cut it out . Set the paper fish in a pan of water. Drop a tiny amount of vegetable oil or detergent into the hole in the fish. What happens?
Cut a 5-cm (2") strip lengthwise from an old newspaper. Holding the strip out straight, give it a half twist (180 degrees) and attach the two ends together. Take a pen and carefully draw a line along the center of the strip. Where do you end up? Is the line drawn on the inside or outside of the paper? Now cut the strip along the line you drew. How many chains do you get?
Slice a small potato lengthwise into several pieces that each have two flat sides. Place some of the pieces in one dish and the rest in another. Fill both dishes with water. Add two tablespoons of salt to one of the dishes, and label it "salt water." Let the potatoes soak for 15 minutes. Compare the potatoes. Is there a difference in firmness? Why?
Draw a picture of your favorite bird on a small index card. On another card the same size, draw a cage. Now tape the two cards, drawing sides out, on opposite sides of a pen. Spin the pen between your hands or fingers. Is your bird still free or did you catch it and put it in the cage?
When the metal spoon taps against the table, it sends a vibration up the string, through your fingers, and into your ears. Your eardrums pick up the vibrations and send them to your brain where they are translated into sound.
All liquids have a certain amount of surface tension, a property that causes a liquid surface to behave like an elastic skin. The vegetable oil or detergent decreases the water's surface tension. If different parts of the fish have contact with different surface tensions, the fish will be propelled.
The amount of air within the bottle is fixed at whatever the atmospheric pressure was on the day you turned the bottle upside down. The pressure on the surface of the water depends on the current air pressure. As the weather becomes drier, the air pressure increases, forcing the water to rise in the bottle.
Through osmosis, water moves from areas of low salt concentrations to areas of high salt concentrations. Adding salt to the water creates a higher salt concentration in the dish than in the potato. Consequently, water in a potato that is soaking in salt water migrates out, leaving behind a limp spud!
Your chain is called a Mobius strip, which is a shape described by a science called topology. When you twisted your strip, the inside and outside became one continuous surface. And when you cut the strip, it became one longer chain but still had only one continuous surface. (Try the experiment again and give the paper a full twist. You'll be surprised by the results.)
It appears to be caged because of how your eyes and brain work. When you see the image of the bird, your brain holds onto the image for a short time--even though the image appears and disappears quickly. The same thing happens with the image of the cage. The two images actually overlap in your brain so the bird appears to be in the cage.