Simple Science
By John Cowens

For more of John's "Simple Science" experiments click here.

Here are some quick and easy science experiments for those dreary winter days when everyone needs a pick-me-up. Have fun!

Red cabbage magic
Cut several red cabbage leaves into tiny pieces. Place them in a cup of boiling water for thirty minutes. Pour the violet-colored cabbage juice into a clear glass. You can now use it for crazy color magic! Line up three clear glasses (or beakers). Discreetly, place water in the first glass, white vinegar in the second glass and a mixture of bicarbonate of soda (baking soda) and water in the third. In front of your students, pour a little cabbage water into each of the glasses. Instantly, your students will notice the first glass containing water remains violet, the second glass containing white vinegar turns red, and the third glass containing bicarbonate of soda turns green.

Explanation:
The violet cabbage dye has the property of turning red in acid liquids, green in alkaline and staying neutral in water. It's fun to find out whether a liquid is acid or alkaline by using detecting substances (pH indicators).

Shooting peas
Place a metal stove burner cover on top of a small plastic cup. Next, overfill another small plastic cup with dried peas and carefully add water all the way up to the brim of the cup. Finally, place the cup of soaking peas on top of the stove burner cover. In a few minutes, the peas start falling out of the cup for over an hour hitting the stove burner cover and creating a strange "rat-a-tat" sound!

Explanation:
The dried peas absorb the water through its skin, the peas swell and nutrients are dissolved (an osmotic process). As space in the cup limits the number of peas, gravity does the rest. This is a great example of how water penetrates the walls of all plant cells causing them to stretch. If the plant does not receive enough water, it becomes flabby and wilts.

Jumpin' pepper and lazy salt
Scatter a teaspoon of coarse salt onto a table and mix it with a teaspoon of ground pepper. To separate the two spices, rub an inflated balloon with a wool cloth and hold it about an inch or so above the mixture. The pepper jumps up to the balloon and sticks to it!

Jumpin' pepper! Kids will get a real charge out of this flavorful experiment.

Explanation:
The balloon becomes negatively charged when it is rubbed with a wool cloth. As a result, the balloon attracts both the pepper and salt. The pepper "jumps" to the balloon because it is lighter than salt. After most of the pepper has been removed, recharge the balloon and move them closer to the salt.

Bonus activity:
Charge a balloon with a woolen cloth and hold it over a small dish of puffed rice. Instantly, the grains jump up and remain hanging on the balloon!

Explanation:
The pieces of puffed rice are attracted to the negatively charged balloon and cling to it for a short period of time. If electrons pass from the balloon into the puffed rice, the grains and balloon will have the same charge. As a result, the puffed rice repels from one another and fly away from the balloon in all directions.

Tying water into knots
With a small finish nail, pierce holes into an empty two pound coffee can five times just above the lower edge so that the first hole is just over an inch (2.5 cm) from the fifth hole. Cover the holes with your finger and fill it with water. When you quickly remove your fingers from the five holes a stream will flow from each hole. If you move your finger over the holes, the streams will join together.

Explanation:
Water molecules are attracted to one another and create "surface tension" or "skin," which pulls the outermost water molecules tightly together. It's this force that holds a water droplet together as it falls down to the Earth's surface. The force of water through the holes in the coffee can is made especially noticeable as it diverts the steams into sideway arcs and knots them together.

Paper bridge
Make a flimsy bridge by placing a sheet of writing paper over two small plastic drinking cups four inches (10 cm) apart. Place a third plastic cup on top of the paper between the two cups. The bridge collapses. Now, fold the paper into an accordion shape (each fold about 1/2" (13mm) wide and place it on top of the two cups. Place the third cup on top of the folded paper. It supports the weight of the cup!

Paper bridges falling down? Try folding your paper into an accordion shape.

Explanation:
Flat surfaces cannot hold as much weight as vertical surfaces. The weight of vertical surfaces is easily distributed over several sloping paper walls and supported in the high-stability folds. A great example of this is the strength that is found in corrugated iron and corrugated cardboard.

Gravity-defying marble
Place a normal-sized marble on a smooth table top. Turn an empty jam jar upside down and place it over the marble. The marble can be lifted into the jar without turning the container right-side up! To do this, make fast circular movements with the jar which, in turn, sets the marble revolving inside the jar.

Explanation:
Centripetal force moves the marble against the inner wall of the jar. Also, the narrowing of the glass jar at its mouth prevents the marble from dropping out as you lift it from the table.

For more of John's "Simple Science" experiments click here.

John Cowens teaches sixth grade at Fleming Middle School in Grants Pass, OR.