Wednesday, December 19, 2007

pH INDICATOR

MATERIALS

Red cabbage
Sugar water
Baking soda
Vinegar
Cups (clear plastic, or paper)
Knife and pan
Stovetop

SAFETY PRECAUTIONS

Should be supervised by an adult due to the chopping with a knife and heating on a stovetop.

PROCEDURE

1. Chop a few leaves of red cabbage finely and place in pot. Cover with water, bring to boil, reduce heat, and simmer until solution is deep blue/purple.
2. Allow cabbage solution to cool. Strain into a jar. After the experiment is over, be sure to save this solution for other experiments. It saves well, covered, in the refrigerator. This is your indicator. If you wish, you may also take strips of white filter paper (such as a coffee filter cut into strips 2-3 inches long) and soak in the juice, and then let dry, to use as indicator strips to experiment with. Still save the juice, however.
3. Explain the term ‘indicator.’ (a substance that indicates if something is acidic or basic.)
4. Mix baking soda with a little water in a cup to make a baking soda/water solution. Label “baking soda”.
5. Pour a small amount of sugar water into another cup and label “sugar water”.
5. Pour a small amount of vinegar into a third cup and dilute with a little water. Label “vinegar”.
6. Ask, “What do you think will happen if we pour our cabbage juice/indicator into these cups?”
7. Add cabbage juice/indicator into each of the 3 cups, recording observations on the chart provided.
8. Discuss acids and bases and how they react with the cabbage juice indicator. Discuss neutral solutions and how they react with the indicator.

EXPLANATION

Cabbage juice is an indicator that indicates if a substance is acid, base, or neutral. If a substance is an acid, the cabbage juice (or strip) will turn pink or red. If a substance is a base, the cabbage juice will turn green or blue-green. If a substance is neutral, the cabbage juice/indicator will not change color. The vinegar is an acid and will turn pink. The baking soda is a base and will turn green.

Sunday, December 2, 2007

Gas Matters

Kids love this dynamic demonstration. Easy and effective!

MATERIALS

Baby food jar
Carbonated water (or clear carbonated soda)
1 tsp table salt

PROCEDURE

1. Fill baby food jar ½ full with carbonated clear liquid.
2. Ask, “Do you think carbon dioxide gas is considered ‘matter’?” “How do you define ‘matter’?” (Has mass and takes up space.)
3. Ask, “What do you think will happen if we add some salt to this jar?”
4. Add 1 teaspoon of table salt to the jar. Observe. Ask, “Why do you think this happened?”

EXPLANATION

The bubbles in the carbonated liquid are full of carbon dioxide. Carbon dioxide gas takes up space. When you add the salt molecules, the salt molecules push the carbon dioxide molecules out of the way. When the carbon dioxide bubbles rise to the top, they bring small amounts of soda with them. Replacing a gas with another substance is called “effervescence.” Gas is considered ‘matter’ because it fulfills the two requirements: it takes up space, and, it has mass (weight).

Friday, November 2, 2007

THREE IN ONE

MATERIALS

Shaving cream
Magnifying glass
Penny
Small plate

PROCEDURE
1. Place a small amount of shaving cream on the plate. Describe it. Is it a solid, liquid, or a gas?
2. Gently, place the penny on top of the shaving cream. What happens? Is the shaving cream a solid, liquid, or a gas?
3. Rub the shaving cream between your fingers. What does it feel like? Does it act like a solid, liquid, or a gas?
4. Examine the shaving cream with the magnifying glass. What do you see? Does it look like a solid, liquid, or a gas?
5. Let the shaving cream sit out overnight. What does it look like now? Let it sit for a few more days. Does it change its state?



EXPLANATION

Some substances exhibit characteristics, or properties, of more than one state, or phase, of matter. Shaving cream feels like a liquid when you rub it between your fingers. It has gas bubbles in it. It keeps its shape and supports light objects and therefore acts like a solid. When you let it sit for a few days, the liquid evaporates and leaves a very thin solid and spaces where the gas bubbles were. The molecules of the gas, the solid, and the liquid, are dispersed throughout each other, each retaining its own properties. This is referred to as a ‘colloid’.

Wednesday, October 17, 2007

CLASSIFYING MATTER

MATERIALS

1 tray per team
At least 2 people
A variety of small objects found around the home (buttons, paper clips, etc.)
Paper towels

PROCEDURE

1. Arrange a variety of small household objects on a tray (about 40-50 items). Prepare one tray per team. A team may consist of 1-4 people. Have at least 2 teams.
2. Each team classifies the objects on its tray into just 2 groups. Do not tell the other team what properties are being used to classify the 2 groups.
3. Now, each team inspects the trays of the other teams and tries to guess how that team classified its matter (example, by color, by size, by material, etc.)
4. Return to your own tray. Cover one of the 2 groups with a paper towel. Now, classify the remaining objects into 2 groups.
5. Now, each team inspects the trays of the other teams and tries to guess how that team classified its matter.
6. Repeat steps 4 and 5 until you cannot classify any further.

EXPLANATION

This is a fun activity with valuable skills learned. Matter is classified according to its properties, in any way the children decide. Each classification system is as valid as the other. There are no wrong answers.
This can also be done with buttons if you happen to have a large collection of a variety of buttons that provide different shapes, colors, materials, number of buttonholes, etc.

Friday, October 5, 2007

MEASUREMENT

TEMPERATURE

MATERIALS

Cup or bowl with ice
Rock salt
Graph paper
Thermometer that reads Fahrenheit and Centigrade degrees
Timer

PROCEDURE

1. Place ice in cup, or bowl, and read the temperature. Record.
2. Sprinkle 1-2 tablespoons of rock salt on the ice. Start timing.
3. Read and record temperature every 30 seconds for 3 minutes (see the chart on the following pages.)
4. Try different bowls. Does the type of bowl (size, metal or plastic) change your answers? Change the amount of salt you added. Does this change your answer?
5. Graph your results with temperature as the ‘y’ axis, and time as the ‘x’ axis.
Have your parents help.

EXPLANATION

After addition of the rock salt, you will notice the temperature decreasing. This is why you add rock salt to the ice in an ice cream machine; it makes it colder which in turn makes it easier for ice cream to form.

Sunday, September 23, 2007

LET'S MAKE CLOUDS

MATERIALS

Glass jar with lid
Ice cubes
Hot water
Flashlight

PROCEDURE

1. Fill jar half-full with hot water*
(*have an adult do this)
2. Place lid upside down on top of jar
Wait a few minutes
3. Now place ice cubes on the lid
Observe. May darken room and shine flashlight
through jar for better viewing

EXPLANATION

You should see moisture condensing on
the sides of the jar, resembling clouds.
When the air is cooled by the ice cubes, the
water condenses and drops back down into
the water.
This is similar to water vapor cooling
in the air high above us, condensing into
clouds of raindrops, and dropping back down
to earth as precipitation.

Monday, September 10, 2007

COLORS AND LIGHT

BEAMING COLORS

MATERIALS

Flashlight
Different colors of balloons, or colored cellophane
Scissors
Rubber band
Dark room

PROCEDURE

1. Cut balloon (or cellophane) and stretch it over the end of a flashlight, secure in place with rubber band
2. Turn on flashlight and beam the colored light to the ceiling, noting its color
3. Repeat steps 1 and 2 using different colors of balloons

EXPLANATION

The balloon works real well as a ‘filter.’ You can also do this with pieces of colored cellophane or plastic. White light consists of red, orange, yellow, green, blue, and violet colors. The ‘filter’ absorbs all those colors except for the one it transmits; for instance, a green balloon is absorbing red, orange, yellow, blue and violet, and transmitting green.

The 8 to 10-year-old probably will not understand the term ‘transmits.’ Use ‘beams’ or ‘sends out’ instead. If the child can picture beaming colors of light out of the flashlight using a filter, this will prepare them for learning the concept of white light consisting of multiple colors, some absorbed and one transmitted, when they are older. Prisms can be used to separate white light when they are older.

Tuesday, September 4, 2007

BUOYANCY

MATERIALS

Modeling clay
Dishpan
Water

PROCEDURE

1. Take a piece of modeling clay and split it into 2 identically sized pieces
2. Take one of the pieces and roll it into a ball
3. Take the other piece and smooth it out into a flat piece, like a little pancake
4. Fill dishpan with water
5. Ask child, “Do you think these pieces of clay will sink or float?”
6. Place both pieces of clay into tub of water at the same time. Observe.
7. Have child communicate observations.

EXPLANATION

If the total area of the object that makes contact with the water is large enough, the object floats. The object must make room for its own volume by pushing aside, or “displacing” an equal amount of liquid. The object is exerting a downward force on the water, and the water is exerting an upward force of the object. The solid body floats when it has displaced just enough water to equal its own weight. This is “buoyancy.” An object immersed in a liquid is buoyed upward by a force equal to the weight of the liquid displaced by that object (Archimedes’ principle.)

Saturday, August 25, 2007

COHESION

WATER ON A PENNY

MATERIALS

One penny
Eyedropper
Water
Liquid detergent

PROCEDURE

Ask, "How many drops of water do you think
you can put on this penny without the water
dropping off the edge?"
Place the penny flat on a smooth surface. With
eyedropper, drip the water onto the penny one
drop at a time, counting the drops, until the
water spills off the edge.
Take same penny and rub detergent on it.
Predict the number of drops of water you can
put on the penny without the water spilling
over the edge.
Using the eyedropper, drip the water on the
penny and count the drops.

EXPLANATION

Water molecules have a strong cohesion, or
attraction, to other water molecules. This
cohesive force of the like-molecules forms the
skin-like surface of the water, called surface
tension. Soap reduces surface tension, causing
less drops to stay on the penny with the soap.

ADHESION

PASS THE PEPPER

MATERIALS

Cereal bowl
Pepper
Liquid dish detergent

PROCEDURE

Fill dish with water
Sprinkle some pepper on top of the water
Ask, "What do you think will happen to the
pepper if we add detergent?"
Drop several drops of detergent into the
center of the water.

EXPLANATION

Adhesion is the attractive molecular force
that holds together UNLIKE bodies in
contact. The water is pulling on the pepper
evenly from all directions. The detergent
reduces the adhesive force between the
pepper and water. The water around the
bowl's edges, untouched by the detergent,
still has its full pulling strength.

Tuesday, January 2, 2007