Summer of Science: DIY Barometer

I swear eventually I’ll blog about more than just science experiments, but once again I’m having health issues, in particular a headache/neck pain/cramping/weirdness.  Deep breathes.

Summer Experiments with Kids

Okay, on with the Summer of Science!  With the storms that have been rolling around the country it seems fitting that we’d be studying weather this month and a big part of meteorology is studying air pressure and the tool for that is a barometer.  The science behind a barometer can be confusing to a child but with just a couple of balloons and jars you can easily explain it.

science experiment for kids
  • two balloons (we used 12” ones)
  • large wide-mouth jar
  • baby food jar or other small jar
  • scissors
  • toothpick
  • glue
  • two rubber bands
cut the balloonsStart by cutting off the bottom of one balloon and the top of another.  Don’t cut them in half, instead cut the top 2/3 of one and the bottom 2/3 of another.

Stretch the bottom piece of balloon over the small jar and secure with a rubber band.  Dab a little bit of glue onto the top of the balloon and apply the toothpick.  Note this portion of the experiment didn’t work for us and barely fit inside the jar.  Wait, did I get to that part, yet?

Homemade Barometer

Carefully put the small jar inside the larger one, stretch the top piece of the second balloon over the large jar’s lid, and secure with a rubber band.
Now comes the fun part, if you push down on the balloon you are increasing the pressure inside the jar and compressing the rubber on the small jar.  It’s supposed to make the toothpick point up, ours didn’t, but it still moved. 

If you pull up on the balloon you are allowing the air to expand, decreasing the pressure so that the air inside the small jar expands as well.  This makes the rubber pull up, and the toothpick point down, ours didn’t, but it still moved.  I already said that, didn’t I?

That’s all folks!  Thursday we’re going to do a quick experiment on low air pressure!

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