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True Story:

At the height of World War II, in 1942, the British Navy had a sudden breakdown in radio communications. The British became convinced that it was a German trick. It turned out to be disturbances caused by sunspots over 93 million miles away.

The True Story of Black Hawk Down from the A&E Video Store.

Cosmos Collector's Edition Boxed set - VHS
Carl Sagan's COSMOS is one of the most influential science programs ever made.

Q. Does the moon have a dark side?

A. The moon does have a far side which is impossible to see from the earth, but it doesn't mean that it's always dark. Each side of the moon is dark for no longer than 15 days at a time.

Q. Where does sound come from?

A. The air is always filled with sound waves. All things give off vibrations, but some have a low frequency which most cannot hear. The reason: it may take 3 minutes to make a single vibration. They may be caused by earthquakes and storms.


Salt and Sugar Move Water

For cells to survive they need to gather water by soaking it up from the surrounding area. These two experiments will show you how sugar and salt move water. You will need an adult, some raisins, a couple of potatoes, salt, a pitcher of water (one for each experiment), a glass jar, a knife and spoon, a saucer (one for each experiment), two bowls that will be used in the salt experiment, and a cutting board.

Sugar Experiment:

Raisins have dead cells, but they have lots of sugar, which pulls the water in from outside. Take a spoonful of raisins, making sure they are hard and dry, then place them into a jar. Add water until the jar is almost filled. How do the raisins look? Probably still, small and dry, right? Use the spoon to stir the raisins, but leave them in the jar. It will take some time before the sugar pulls in some water. Wait three hours or more before taking another look at the raisins. What do the raisins look like now? They ought to be swollen and puffy, because the sugar in the cells have taken in the surrounding water. Sugar moves water.

Salt Experiment:

In the sugar experiment you discovered how water moves inside cells that have sugar, but this experiment will show you what happens when water is moved outside of cells by using salt. You will need the potatoes for this one.

You will need an adult to help peel the potatoes and to slice them into several average-size pieces. You ought to feel the hardness of the potatoes before putting them in the bowls, so that you can compare the way they feel before and after. Fill both bowls with water: add salt to one, but leave the other with plain water. You will need to stir the salt to help it dissolve. Add pieces of potatoes to each bowl, then let them sit for around two hours. After two hours, pick the potatoes pieces up and compare them to one another. What do the potatoes feel like? The potatoes in the salt water have lost cells causing them to feel soft and rubbery. The potatoes in the pure water ought not be unchanged to the touch.

Can you think of other ways to experiment with water movements into or out of cells?

Sources:

1. Shreeve, Tim. Discovering Ecology. Sceptre Books Ltd: London. 1982

2. Editors. The World Book Encyclopedia. World Book-Childcraft International, Inc: Chicago. 1990








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