Sunday, May 9, 2010

Science Experiment – Air Pressure / How Birds Fly

{I have been having the weirdest problems with scheduling posts lately.  You might have seen this post in your reader last week, and then had it disappear if you tried to look at it on the actual blog.  Too much mommy brain + too little coffee = crazy and incompetent.} 

As a final (whew!) bird-related activity, we did a little experiment to show how air pressure works using two balloons.

An experiment and balloons?  It doesn’t get much better than that if you are a 3 year old boy. :)

The way birds are shaped and the way they move their wings causes the air to move more quickly above them.  Quicker-moving air = less air pressure, so the air beneath them exerts the greater pressure and keeps them aloft!

To demonstrate that fast-moving air lowers air pressure, I blew up two small balloons, tied a length of yarn to each one and then hung them from our sofa table so they were level with one another.  You want them to be about 3 inches apart.  April 2010 031

Ask your child to think about what will happen to the balloons if he blows a straight line of air between the two of them.  When we blow directly on an object it moves away from the force of air, so it makes sense (sort of) that the balloons would move apart.  M was sure they would get “wider apart”, as he put it.

Here’s what happens:April 2010 035
They move toward each other and bump!  The still air on the sides of the balloons is exerting more pressure than the fast moving air between them, so it pushes them together! Pretty cool, huh?  ;)

You can do this with a strip of paper that you hold near your bottom lip – blow air directly over it and it should rise.  Or try two cardboard tubes on a table side by side with an inch of room between them; use a straw to blow air directly between them and watch them roll towards one another!

For more science fun with kids, go see Ticia’s Science Sunday posts!

Have a beautiful and blessed Mother’s Day! :)


  1. And I've been looking for a physics concept to go with our birds week... Thanks for the idea!

  2. Great explanation of the science of air pressure, and birds' flight!

  3. Huh, didn't know that about the balloons. I knew the general idea of why birds flew, but not a good explanation.
    And yes I do remember seeing this briefly and going over to try and comment and it being missing.

  4. I real fun interesting way to learn more about birds.


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