Visit the control tower of an airport. Learn about the principles of flight. Tour an airplane and look at all the control dials.
Materials needed: a clean glass, 1/4 cup of water, a teaspoon of salt, red and green liquid food coloring, a strip of paper towel about one inch wide, a pencil
Instructions: Mix together a few drops of the red and green food coloring. Make a spot on the paper towel with this mixture about one inch from the bottom. Let dry.
Pour the water into the glass and stir in the salt. Place the pencil across the top of the glass. Hang the paper strip over the pencil so that the end of the paper with the spot just dips into the water.
Wait a few minutes, and the water will slowly climb up the paper. The spot will separate into patches of red, yellow, light green and blue.
Why? The food coloring is a mixture of different colored chemicals. As the salt water climbs up the paper it dissolves the chemicals. Some chemicals rise higher than others.
Separating chemicals this way is called Chromatography. When the chemicals are separated they can be identified more easily.
Atmospheric Pressure Experiment
Simon Kenton Council
We live under a blanket of air called the earth's atmosphere. The air in the atmosphere exerts pressure of almost fifteen pounds per inch on every surface of earth.
Hanging Water - Fill a glass to overflowing and lay a piece of cardboard atop it. Support the card with one hand, turn the glass upside down, and remove your hand from the card. The card does not fall. It remains on the glass and allows no water to escape. Why? The air pressure from below the cardboard is greater than the pressure of the water above and presses the card tightly against the glass.
Air Pressure Experiment
If we compress air (put more air into the same space0, we will increase its pressure and can use it in machines. Your bike tires use compressed air to give you a smooth ride.
Balloon in Bottle - Place a deflated balloon inside a two-liter bottle, with the lip of the balloon over the top of the bottle. Try to blow up the balloon. What happens? Air pressure inside the bottle increases as the balloon takes up space, so air pressure is fighting against you. To inflate the balloon, you would need to compress the air trapped between the balloon and the bottle. To compress air requires force. The human lungs are not strong enough to inflate the balloon and to compress the trapped air.
Crystal Clear Project
Materials: Salt, sugar, Epsom salts, laundry detergent flakes, 4 glass jars, 4 spoons, magnifying glass, thread or thin string, very hot water, pencils, paperclips, food coloring.
- Fill a jar half full of very hot water. Stir a cup or more of salt, a little at a time, until no more will dissolve.
- Rub some salt onto a piece of string. Tie it around a pencil, tie a paper clip to the other end, and drop into the water. Lay the pencil across the jar.
- Put the glass in a cool place where it won't be disturbed. Do not touch the jar or the pencil. Watch for a few days.
- Repeat the process with Epsom salts, sugar, and laundry flakes. Try adding a little food coloring to one of the solutions.
The salt dissolves in the hot water. Cold water can't hold as much salt in a dissolved form. As the water cools, the salt forms again on the string. Observe each type of crystal with magnifying glass.
Experiments in Pascal's Law
Holding Water in a Straw - Place a straw in a glass of water. Seal the top of the straw with your finger and remove from glass. Water remains in the straw. Why? With your finger you are lessening the air pressure over the straw. The greater pressure of air under the straw can hold the liquid inside the straw.
Plugging the Gaps - Fill a pop bottle with water, put a straw in the bottle, and seal the tip of the bottle with clay, taking care that the straw is not bent of crimped. It will be impossible to suck water out of the straw. Why? The air pressure inside the straw is reduced, so that the air outside the straw forces the liquid to remain where it is.
Drinking from Two Straws - Hold two straws side by side, one inside the glass and one outside the glass. If you try to drink the water, it will not enter the straws. Why? The second straw equalized the air pressure inside your mouth.
Invite a dietitian to your den meeting to talk about how and why foods cook. Why do you add yeast, salt or soda to recipes? What happens if you forget part of the ingredients? How does a microwave oven cook foods? What other ways are there to prepare food?
Do some cooking in your kitchen and then sample the foods. (Microwave cupcakes, hot-air popped popcorn, cookies baked in the oven, grated cheese broiled on bread, steamed pudding, YUM!)