Demos Live
We are introducing a new category today, the Make Your Own Demo file is officially open.  So, for those of you who change your own oil, scrapbook, quilt, or otherwise, do it yourself, we are going to offer a series of science demostration ideas that you can make and take to school.  The first one up is called Atoms in a Cage.

Why Are We Doing This Lab?
This simple model because it allows the kids to "see" solids, liquids, and gases.  It can also be used to show how the atoms in solids, liquids, and gases act and react to temperature changes and transition between states.  When you are done with the lab the kids will know that the number of atoms do not change as a material passes from one state to another; rather, it is the speed, energy, and vibration of the atoms in the material that change. 

The finished demo (pictured to the right) takes about 20 minutes to assemble and is going to cost you about $ 5.00 (on the high end).  The nice thing is that it will last for years if you take care of it, which means that you refrain from beaning that obnoxious kid in the front row and putting a permanent dent in the side.  The rabbit cage wire and zip ties can be picked up at any farm supply, home improvement or hardward store and the dylite balls are available at most craft stores.

Demo Materials
1     Square of rabbit cage wire, 18” by 16” by 1/2”
24   Dylite balls, 1/2” diameter
1     Wire cutter
12   Zip ties, electrical, 6”
        and
1    Multispeed hair dryer   
1    Extension cord
1    Hot plate
1    Tea kettle
        Water and ice cubes

Building Your Model
1. This kind of wire can be purchased at any home improvement store and is usually found in the fencing section in rolls that are 24” to 26” tall and 5’ to 25’ long.  A small roll, 5’ long, should cost you five or six bucks and give you enough material to make four of these demos.

2. Once you cut a piece from the roll that is 12” by 18”, roll the wire into a cylinder that is 18” tall and 4” in diameter.  Use the electrical zip ties to connect the two sides together and hold the cylinder in place.

3. Cut two 4” diameter circles from the remaining screen.  If you are going to err, slightly larger is better than too small.  The circles need to fit over the ends of the cylinders.  Place one of the circles on one end of the wire cage. Use the electrical zip ties to connect the wire circle to the bottom of the cage.

4. Tip the cage on the end  that you just tied in place and fill it with the dylite balls. These can  be purchased at any craft store,  and should be one-half to three-quarters of an inch in diameter.  Smaller than that and they get stuck in the holes in the wire; bigger than that and the atoms are too heavy to fly around effectively.

5. Zip tie the other circle to the other end of the cage.  Your model is now complete.  If you were crafty enough you should be able to enter the state fair in addition to teaching chemistry to kids. 

The Demos
1.  Present an ice cube to the class and ask them which particular state, solid, liquid, or gas, is represented.  Solid will be the answer, without too much of a stretch.  Place the ice cube, along with its pals, in the kettle on the hot plate.

2.  Hold the “molecule cage” above the hair dryer, but do not turn the blower on. Indulge us a bit; this is going to be our model for a solid material.  Explain that the white spheres represent atoms.  Have the kids observe the cage with “atoms” resting on the bottom.  They are still and in a relatively orderly fashion.

3. Now present a plastic glass full of water to the class and ask them which particular state, solid, liquid, or gas, is represented.  Liquid will be the first choice.  Pour the water into the kettle on the hot plate. Turn the hot plate on. 

4.  To demonstrate the action of the molecules trapped in the cage as heat is added, turn the blower on low, wave it under the bottom of the cage, and observe as the balls begin to randomly bounce throughout the lower half of the cage. Move the hair dryer back and forth a bit.  This is our liquid state.

5.  As the kettle is heated, the ice will melt and the water will eventually turn to steam which will escape from the kettle and make a cool noise announcing its departure.  Ask the kids which particular state, solid, liquid, or gas, is represented by the steam.  Gas is the only choice left. 

6. Turn the blower on high and watch the chaotic molecules speed up as the temperature is increased. This would be our gas phase. 

How Come, Huh?
Again, not to beat a dead horse, but you are studying the physical properties of matter.  At room temperature, water is a liquid.  Stick it outside in winter and you have a solid in the form of ice and toss it on a sidewalk in the middle of summer and pretty soon you have water vapor.  The  state that a material is in is characterized as a physical property that can be observed and used to describe that material.
In the first model (representing a solid substance at room temperature), the spheres in the cage did not move very much.  If we could see atoms in real life, they would be like that.  Next comes the liquid state.  The dryer is turned on low and the balls start to move around freely in the bottom third of the cage.  They bounce into the sides of the basket more often (this is called pressure)  and are more fluid.  Finally, we crank the dryer up to high and the balls are flying everywhere. They slam into the sides of the basket, increasing the pressure inside, and fly all around.  This is our gas phase. Three states of matter, all physical properties  that describe matter.

The Infamous Product Tie-in
We have the full lab write up available so if you would like to extend the learning and fatten this demo up a bit we have a lot more information foryour.  And for those of you who are not crafty, handy, or inclined to make your own stuff when you can buy it for a very reasonable price, we offer it here.