Asia-Pacific Forum on Science Learning and Teaching, Volume 10, Issue 2, Article 2 (Dec., 2009)
Undergraduate and masters students' understanding about properties of air and the forms of reasoning used to explain air phenomena
Demonstrations and Hands-on Activities that were Included in Class but that were not Analyzed for type of reasoning
Property of air
Air Occupies Space
Mystery bottles: Insert the air pump tube into the balloons and try to blow them up one at a time. You will need to push the tube in fairly far and pinch your hand around it to prevent air from escaping. Do the two balloons react differently? Can you explain why? Can you figure out a way to keep the one balloon blown up when the air tube is removed?
Materials: Air pump, balloons, two-soda bottle (one with a tiny, hidden pin hole)
Air Exerts Pressure
The mysterious hot test tube: Fill a jar with colored water. Put a little water in a test tube and boil it vigorously. Then invert this test tube immediately in the colored water. What happened? What is in the test tube besides the water before heating? What happens to water when it is boiled? Materials: A test tube and test tube holder, a jar, an alcohol burner or other source of heater, food coloring.
The balloon and the flask: Put a little water in a flask and heat it to boil vigorously for a while. Take the flask off the fire and immediately place the balloon with the mouth over the flask’s mouth. Let it cool slowly at room temperature. Watch what happens to the balloon. What is in the flask besides the water? What is the steam doing to the air in the flask? Why did the balloon do what it did?
Materials: A flask, a balloon, plate or burner & stand.
Heated soda pop can: Put a little water in an empty coke can and heat it to boil vigorously for two minutes. Take the can with boiling water off the heat and invert immediately in a cold-water container. Watch what happens. Try to explain the changes in the can.
Materials: Soda pop can, hot plate or burner, stands, and pot holder or glove to protect hands.
Boyle’s Law: Relationship between volume & the pressure of a confined gas
Water in a syringe: Fill a syringe one-third full of colored warm water, then put the cap on it. Now, pull the piston. What happened? Try to explain your observation.
Materials: A syringe, warm water, and food coloring.
Bernoulli’s Principle: The faster the flow of a fluid (air), the lower the pressure it exerts
A discrepant funnel: “How can I pick up the ball with the funnel without sucking through it? I may not touch the ball” Pick up the funnel by the stem; place it over the ball and blow through the stem, lift the funnel while blowing. What happens when we stop blowing? Is it possible to blow the ball out of the funnel? Where is the air moving fastest when we blow the ball out of the funnel? What is the flowing air creating that stationary air doesn’t? Materials: One long stem funnel, one ping-pong ball.
Hands-on Center Activities
Property of Air
Air Occupies Sapce
The air catcher: Take the garbage bag, open its mouth, and move the bag with two hands back and forth. Then quickly close the mouth of the bag with a twisting motion. What was filling the bag? Would the material in the bag be the same if you blew into it?
Materials: Plastic garbage bags.
Cards over a target: Hold a playing card horizontally about a meter (yard) over a target, which can be a sheet of paper, notebook or a box. Then let it drop on to the target. Observe what happens. Now, hold the playing card vertically at the same height and drop it straight down onto the target. Do the cards get into/onto the target or drift away? Why? Materials: Playing cards, box.
Blowing over a strip of paper: Make a fold at one end of the paper strip. Hold the strip near the chin and blow over it. What do you observe? What will happen if you blow against the underside of the paper?
Materials: Strip of paper about 15x3cm.
Blowing under a paper bridge: Place a sheet of paper between two books. What will happen if you blow hard under it? What is different about flowing air compared to stationary air have?
Materials: A sheet of paper, and books or folders.
Two soda pop cans on straws: Spread the straws parallel to each other on the table and leave about 1/2 cm gap between them. Place the two cans upright about 2 cm from each other on the straws. Now, blow hard in between the cans. What happened? What will happen if you blow more gently? What will happen if you place the cans different distances apart, such as 5, 10, 15, and 20 cm away from each other, and then blow? Materials: Two empty soda cans, two dozen drinking straws
Ping-Pong ball and a fluorescent tube protector: Hold tube slightly up from the floor. Drop the ping pong ball into the tube. Turn hair dryer on high and blow across the top of the tube. Experiment with angles. Observe what happens.
Materials: Hair dryer (1875 watt), ping-pong ball, and clear plastic tube (sold in hardware store as a protective cover for a fluorescent tube).
Illustrations by Christopher Jarrett and Karen Kimble
Copyright (C) 2009 HKIEd APFSLT. Volume 10, Issue 2, Article 2 (Dec., 2009). All Rights Reserved.