Water Cycle - Atmosphere (1)
Lab

   
OBJECTIVES:
  • Discovering that air is all around us.
  • Experimenting with air.
VOCABULARY:
  • air
  • atmosphere
MATERIALS:

Students use pinwheels to move air. 

 

BACKGROUND:

Pure air is colorless, odorless, and tasteless. It is made up of nitrogen (78%), oxygen (21%) and argon (0.09%).  The remaining 0.1% is made up of carbon dioxide and a number of other trace gases.  The water vapor content (not included in these figures) varies widely.

Air is found everywhere that first graders are likely to venture.  It is concentrated near the surface of the Earth, but gets thinner at mountain tops.  Air is not usually found inside the earth's crust, unless it is trapped in caves.  The higher you get up in the atmosphere the less air you find, until there is a point where there is no air.  

If you go in an airplane you need to bring a source of air, because the air is so thin and does not contain enough oxygen.  However, airplanes can still fly because the air flowing over the top of the wing (which is curved) is going faster that the air passing over the bottom of the wing (which is straight).  When air goes faster, the air pressure is less.  Therefore, air is pushing up on the bottom more than it is pushing down on the top, and the plane rises.  First graders can probably handle an explanation that simply says that air going fast over the top of the wing lifts the wing.

This lab will try and prove that air is something that you can capture and hold.  Although air is all around us, young children donít quite understand that meaning.  

PROCEDURE:
  1. The first experiment for students is to prove that there is air.  Catch some air in a plastic grocery bag and close it.  It will blow up.   Ask the children what is in the bag, and tell them that this is one way of knowing that there is air in a particular place.  Ask them if they can think of places in the room where there is no air.  Give each a bag and have them check it out.  Discuss what they found.  Emphasize that air is everywhere.  We need air to live.  
       
  2. The second part of this activity will have students experiment with a pinwheel.  They will observe that air can make a pinwheel move without blowing on it.  Ask the students to find out which way they can move to make the air move the pinwheel the fastest.  Give them some clues.  Tell them to move the pinwheels side by side, up and down, twirl around, move it in a figure eight, ellipse, or any other movement.  (Twirling around tends to produce the fastest motion). You may want to do some of this exercise outside and then inside without wind.  

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