Thursday, October 11, 2012

Science: Weather

The first science topic we learn about in fourth grade is weather.  We start out by learning that weather is made up of three ingredients:
air + water + sun
Then we learn about each piece.  So far, our focus has been on air.  We have done two experiments to prove the properties of air.  

The first one we did proved that air takes up space. 

 First we crumpled up a paper towel and stuck it in the bottom of a small plastic cup.  We had to make sure it wouldn't fall out when we held it upside down.  Then we filled a larger cup part way with water.  

After that we made predictions about what we thought would happen if we turned the little cup upside down and pushed it straight down into the larger cup.  The students had many different hypotheses.  Some thought the paper towel would disintegrate.  Others thought it would just get really wet. A few thought it might stay dry.

Then we tested it out. 
We discovered that the air that is trapped in the cup pushes the water out of the way and keeps the paper towel dry.  That way we proved that air takes up space.

After that, we tested to find out if air has weight. We filled got two non-latex gloves (Because of allergies, our school is latex free.  Otherwise we would have used balloons.), two clips, and a balance scale.  
We squeezed all the air out of one glove and then clipped the opening closed.  The other glove we blew up like a balloon and then clipped that one so the air wouldn't get out.  When we made predictions this time, the kids almost unanimously thought that the glove filled with air would be lighter than the one with no air.  This is because of their experience with helium balloons.  
Everyone was pretty surprised that the air-filled glove was indeed heavier than the glove without air.  We then talked about how the air is pushing down on us all the time, but we are used to it.  Just like your clothes don't feel heavy when you wear them, or people with long hair don't feel like their head is being pulled down all the time, we get used to the weight and don't notice it.  

I know the kids are really looking forward to our field trip next week (Tuesday, Oct 16) to Blue Hills.  There we will get to see some of the weather measuring tools we've learned about being used by real meteorologists.  I just hope it doesn't snow like it did last year!  Even if it does, it's still a lovely walk.

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