Level: Elementary to Middle School
Time involvement: 10-20 minutes
Materials: Garbage bag and vacuum cleaner or blower with an input connection. Hose connected to vacuum inlet. Demonstrates the power of the atmosphere by enclosing a child in the bag, (HEAD MUST BE OUTSIDE!) Remove shoes, sit “Indian style”. Very safe but remind kids of safety, nothing over the head EVER! If an adult wishes to try the demo, but bag is too small, an arm or leg can be substituted to give a sense of the feeling experienced by kids.
Discussion: By removing some of the air inside the bag the effect of normal atmospheric pressure will be felt. Why is there air pressure? The blower/vacuum cleaner produces a very weak vacuum compared to the actual pressure of the atmosphere. At sea level the pressure is almost 15 pounds per square inch. This is the result of air molecules stacked up over our heads to a depth of over 20 miles. Therefore, given the surface area of even a small child, a complete vacuum would be fatal. This lesson teaches the concept of the Atmosphere in a very tactile way. Without an atmosphere Earth would be a lifeless planet. Air allows sounds to be heard, respiration (breathing) of animals and plants can occur. Animals can communicate with sound waves in air, aromas are used for mating or defense. Winds can carry moisture from the ocean and lakes to dry inland areas allowing crops and food production. The beauty of a sunset or rainbow would never be seen without an atmosphere.
Notes: This is a popular favorite for younger kids. Apprehensive for the first child then most want to try it. Remove shoes first. Requires adult assistance, caution safety. A companion demonstration is the suction cup table lift.
Learn more: The Atmosphere is a huge topic. A current well-written book by the science writer William Bryant Logan, is AIR: The restless shaper of the World. Spanning topics from how the weather on D-Day contributed to the Allied victory to how certain spiders spin webs that can catch breezes and send the spider traveling great distances, the book is filled with the biological implications of the atmosphere. Absorbing and thoughtful, other books by the author are OAK, and DIRT.