Growing in Grace

What is Air?

Today we did some experiments with air to test out its properties and begin learning more about this invisible stuff that surrounds us.  We began by seeing if air is a real thing that takes up space.  It is easy to answer that question by blowing up a balloon or filling a bag with air and then tying it off.  Not only can air take up space, but it can do work…like lift about 30 pounds with no problem!     

Next we wanted to see if air weighs anything, so we taped a deflated balloon and an inflated balloon to opposite ends of a ruler.  We held the ruler evenly to see which side would drop down, indicating the heavier load and the inflated balloon did weigh more.

Then we did a great experiment used to prove further that air is real and takes up space.  We put a balloon inside a soda bottle with the nozzle around the top.  Then we each took turns blowing into the balloon trying to get it to inflate.      It was no use; they weren’t going anywhere!  The bottle was already full of air, so there was no room for more air to come into the bottle via the balloon.  We determined that to get the balloon to blow up, we had to get the air already in the bottle out.  To do that, we put a small hole in the bottom of the bottle.     Once there was a way for the air to escape, blowing into the balloon caused the air in the bottle to blow out the bottom and there was room for the balloon to inflate with the new air.    And, once you got the balloon inflated, you could plug the hole in the bottle and remove your mouth from the nozzle and the air would stay in the balloon.  The bottle was still full of air; some of it inside the balloon and some of it outside. 

      With the hole plugged, there was no air trying to come back in and push out the balloon air.  You could look into the nozzle and see down into the inside of the inflated balloon.  Cool!

The last experiment we did was to see what happens when air gets hot.  We put a balloon over another soda bottle.  Those balloons and bottles came in handy today!  We placed the bottle in a pot of hot water and watched to see what would happen.  It only took a minute for us to see a reaction.  The balloon began to inflate on its own!    We discovered that warm air expands, or takes up more space, and the air in the bottle was taking up more space than when it was cook and needed some place to go.

We had one additional experiment that failed after several tries with the kiddos and I.  I went through three eggs, a melted plastic bottle, several sheets of paper, and about 30 matches before we put it away for the afternoon.  We did, however, get it back out when dh came home and he saved the day and helped us do it correctly.  It is about air pressure, and since we don’t understand the physics behind it just yet, I’ll save it for later in the week!

Tags: School Days

3 Comments to What is Air?

Leave a comment