Grade: 2
Strand: Understanding Earth and Space Systems
Topic: Air and Water in the Environment
Expectations:
1.
Investigate, through experimentation, the characteristics of air and it’s uses.
2.
Identify air as a gaseous substance that surrounds us and whose movement we feel as wind.
3.
Use a variety of forms to communicate with different audiences and for a variety of purposes.
4.
Describe ways in which living things, including humans, depend on air.
Materials Required:
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Plastic bags (various sizes) OR ziplock bags
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Straws
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Objects of varying masses (ex. Books, textbook, school supplies, shoe)
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Tape (masking or duct preferred)
Procedure:
1.
Tape a plastic bag shut around the end of a straw. Ensure that the bag is completely sealed (and deflated).
2.
Have students make a prediction: When I put an object on top of the bag and blow into it, will the bag inflate and lift the object, or stay deflated because the object is to heavy?
3.
Blow air through the straw and into the bag.
4.
Have students discuss what happened.
5.
Deflate the bag, and then try the experiment with heavier objects.

Scientific Explanation
The air is able to lift up a heavy object, because it is being blown into an enclosed space. When the bag fills with air, the air becomes compressed. This means that there is pressure on the container from the outside. When air is compressed, that is, forced into a smaller space than it normally occupies, it has tremendous expansive pressure.
In our experiment, this is seen by the air pushing up on the bag, which in turn pushes up on the object and lifts it.
Scientific Terms:
1.
Compression: a reduction in volume followed by an increase in pressure.
2.
Air pressure: the force exerted on you by the weight of tiny particles of air (air molecules). Although air molecules are invisible, they still have weight and take up space. Since there's a lot of "empty" space between air molecules, air can be compressed to fit in a smaller volume. When it's compressed, air is said to be "under high pressure".
References: http://www.youtube.com/watch?v=uWPYNhdeyWw&feature=related http://science.howstuffworks.com/air-info.htm http://kids.earth.nasa.gov/archive/air_pressure/ http://pbskids.org/zoom/activities/sci/airlift.html
Opportunities and Other Considerations
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As an extension on this activity, students can design a poster that describes how they could use this experiment in real life. (I could use an air bag to lift the mattress up on my sister’s bed to find her diary).
Have students brainstorm where they can find compressed air, and it’s use.
Example: bike tires and air bags.
Presented and Created By Aaryn Coutts and Jessica Doan