ИНЯЗ

YOU WILL NEED

• Five identical plastic bottles
• Water

HERE'S HOW

Fill five identical plastic bottles with varying amounts of water. Arrange the bottles in order from most to least full. Blow across the top of each bottle and compare the different sounds you make.

 WHY?

Changing the amounts of air and water in the bottles lets you change the pitch—how high or low the sound is. When you blow across the tops of the bottles, you are making the air inside vibrate. In bottles with more air, vibrations are slower, so the pitch is lower.

YOU WILL NEED

• A piece of paper
• A paper clip
• Thread
• Clear tape
• Scissors
• A strong magnet

HERE'S HOW

Cut a paper kite shape about three inches long and attach a paper clip to one corner. To the opposite corner, tape a piece of thread about eight inches long. Tape the other end of the thread to a flat surface. Use a strong magnet to pick up the paper clip and extend the string to full length. Hold the kite between your fingers and slowly move the magnet away from the paper clip. When you release the kite, it “flies,” unattached to the magnet.

WHY?

Magnets have a magnetic field, an invisible force that attracts some kinds of metal. Metal objects within the magnetic field do not have to touch a magnet to be pulled by magnetism.

• Four raw eggs
• Pot
• Bowl

HERE’S HOW

1. Boil two eggs in water for ten minutes until they are hardboiled.
2. Cool the eggs under running water, then chill them in the refrigerator.
3. Put several raw eggs into a bowl with the boiled ones. Ask a friend to sort the cooked eggs from the raw ones—without cracking them! Can't do it?
4. Show your friend how: Spin each egg on its side one at a time. Let the egg spin for a moment, then stop it and immediately release it. The raw eggs start to spin again (just a little), but the cooked ones don't.

WHY?

The raw egg starts to spin again because it has liquid yolk and egg white inside. Even when you stop the egg from spinning, the liquid inside keeps turning because it is not attached to the shell.

YOU WILL NEED

• An apple
• Half of a lemon
• Shallow bowl
• Water
• Knife (ask a parent for help)

HERE'S HOW

Peel and slice an apple. Cover one slice with water in a shallow bowl. Sprinkle a second slice with the juice of half a lemon. Leave another slice exposed to the air. Wait about an hour, then compare. The slice with nothing on it turns brown.

WHY?

When an apple is cut open, chemicals inside the apple combine with oxygen from the air to form a brown coating. The coating keeps oxygen from getting deeper into the apple. Water protects the first slice from oxygen in the air so it stays white. Vitamin C in the lemon juice binds with oxygen, keeping oxygen away from the second slice, so it stays white the longest.