Where's the Air?

3.7 based on 189 ratings

What You Need:

  • Glass jar
  • Lit candle

What You Do:

  1. Have your child place the jar on a tabletop.
  2. About ten inches behind the jar, place a short (4-inches tall or so) candle upright, and light it. The flame should be entirely centered behind the jar—not over to the side, and not taller than the jar.
  3. Invite your child to make a scientific guess—a hypothesis—about this candle. If your child blows hard on the jar, not the candle, will anything happen? Will the candle flame stay the same?
  4. Now ask your child to blow hard on the jar on the opposite side of the candle—so that the jar is directly in front of her with the candle directly behind it.
  5. What happens when she blows on the jar? The candle should go out immediately! (If it doesn’t, move it a little bit forward so it’s closer to the back of the jar). How did this happen? Did the air travel through the jar? Ask your child what she thinks. What happened was that the air separated when it hit the sides of the jar and flowed around its curves to come together again and form a stream that hit the candle. Sure, you couldn’t see it, but it happened!

When air comes into contact with objects, it flows around the contours of the object it hits, creating forces that can lift kites and blow out candles. In fact, the same property is what make flying a plane possible! This experiment will not only amaze your child, but it will also get her interested in learning some basic physics concepts regarding the important properties of air.

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