Fire is a chemical reaction that creates light and heat from oxygen and fuel. A lit candle needs to draw oxygen from the air in order to continue burning. If you limit the amount of air available, the candle's flame eventually goes out once it uses up all the oxygen. Here's a science experiment that gives your child a chance to see this concept in action, with a little math and writing practice thrown in.
4 glass jars in different sizes (make sure they're large enough to fit over the tea candle)
Pen or pencil
What You Do:
Begin by explaining to your child that fire needs oxygen from the air in order to burn. Ask her what she thinks will happen if you limit a candle's oxygen supply.
Light the candle and place one of your jars over it. Watch and wait until it goes out. Was this what she expected to happen? What does she think will happen if you place a larger jar over the candle? How about a smaller jar?
Put the jars in a row from smallest to largest, and help your child write the numbers 1, 2, 3, and 4 on the sides in permanent marker.
Ask her to estimate how long it will take for the candle to go out as you place each jar over it. Make a table like the one below to record her estimates.
Light the tea candle, and place the first jar over it. As you do so, have your child start the stopwatch. How long does it take for the candle to go out? Record the actual time next to her estimate.
Repeat step four with the three remaining jars.
Compare your child's estimate to the actual length of time each candle burned. Did she predict that the candle would burn longer under larger jars? If not, point the pattern out and explain that the more air inside the jar, the longer the candle is likely to burn.