It isn't good to play with fire, but there are some kinds of things we need to know about fire, which require experimentation. None of these experiments should be done without the supervision of an adult.

Since we never handle dry ice with our bare hands, we will use tongs to place several pieces of dry ice in a dry beaker.

Stand a short candle in another beaker and light it. (The candle can be stuck to the bottom center of the beaker--or jar--by dripping a little melted wax into the jar, wait a minute or so, then, blow out the candle, and push the bottom of the candle onto the spot of wax. Then, light the candle again.)

Be sure the tip of the candle is shorter than the beaker (or jar), so that the flame of the candle is actually inside the beaker.

After the dry ice has sat in the first beaker for a few minutes, hold that beaker over the candle and tilt it as if to pour something out.

You will see that the candle flame is extinguished. That is because we poured carbon dioxide onto the flame.

The dry ice is actually frozen carbon dioxide. As the carbon dioxide changes into a gas, it remains in the beaker, rather than rising into the air, because it is heavier than air. When poured onto a burning candle, carbon dioxide pushes the air out of the way and smothers the flame.

Similarly, a jar containing a vinegar and soda solution can be tipped so that the gas produced by the mixture -- carbon dioxide -- flows down a creased strip of paper aimed at the
candle flame.

An alternative method is to light a candle set in a wide mouth jar with an inch of water on the bottom. Add several teaspoonfuls of baking soda to the water, then pour some vinegar into the solution. As the bubbles rise and the amount of carbon dioxide increases sufficiently, the candle will go out. Many fire extinguishers use carbon dioxide to put out fires.

Perhaps all the science classes could assemble outside, and the school custodian could demonstrate a fire extinguisher by putting out a small bonfire. We'll ask if that could be done.