Talk Science PD is a blend of web-based study, opportunities to try ideas in the classroom, and face-to-face study group meetings designed to help teachers The Inquiry Project research investigates students' developing concepts of material, weight, volume density, matter, and states of matter from ages The project is founded on a learning progression for matter and material and brings together research, curriculum, assessment, and profession development.
Talk Science is scalable, web-based professional development to deepen students' scinece understanding through better science discussions. Having established that air is matter in the last lesson, this investigation explores some properties of air, a gas.
If you have added air to the tires of a car or a bicycle, you have had some experience with compressed air. It takes some effort, but it's possible to squeeze a large volume of air into a significantly smaller space. This is not true for liquids or solids, which are essentially incompressible. What is it about air, and gases in general, that allows it to be compressed?
In comparison with solids and liquids, the individual particles atoms or molecules of any gas are quite far apart from one another, with nothing but a vacuum in between them. Therefore, when pressure is applied to a gas, the particles can be squeezed closer together. Can students envision what might happen at the microscopic level to explain why air is more compressible than water? Enlarge Notebook Sample. Look for evidence of students explanations in their annotated notebook entries on the page Explaining the difference in compressibility of water and air.
As you interpret student work, remember, students have not yet viewed air with the Particle Magnifier. They are basing their ideas on first—hand experience compressing air and water and using the Particle Magnifier to explore particles of water and ice. A next step might be to ask students if they think ice would be compressible or not. Today students continue to explore the properties of air. Students compare the compressibility of air and water and then develop an annotated drawing that responds to the question, "How do you explain the difference in the compressibility of air and water?
By the end of this investigation students will understand that, in contrast with liquids and solids, air is observably compressible and will make a drawing to explain their observations. Now that air has been established as matter, students begin a list of air's properties. Introduce the investigation question:. Record properties of air that students can identify.
As they mention a property ask for evidence or reasoning that supports their claim. Save the list of properties; students will add properties as they continue their investigation of air. Introduce the term compressible - able to be squeezed or pressed into a smaller size or volume. One property of a rock is that it is not visibly compressible. One property of a sponge is that it is visibly compressible. Explain to students they'll be exploring the compressibility of air and how it compares with the compressibility of water.
Have students predict and explain their reasoning in their Science Notebooks, [Predicting the compressibility of water and air]. Students only need a minute or two to explore the compressibility of air with the syringes. Collect the syringes when they are finished.
Note: As students explore the compressibility of air, they may become interested in whether or not the syringe plunger returns to the exact same spot once it has been released. It may not, due to friction between the rubber seal and the plastic barrel of the syringe, or because a tiny bit of air leaked out between the syringe and the palm of the hand.
Neither of these possibilities should distract from the big idea that air can be squeezed into a smaller space, and will expand again once the plunger of the syringe is released.
Move from group to group with two plastic buckets each holding two capped water-filled syringes and two capped air-filled syringes. Under your supervision, give four students at a time an opportunity to compress water and air in syringes.
Do you want to see if these principles really work? Try one or more of the following experiments:. Water Glass Trick. Fill a cup one-third with water. Cover the entire mouth with an index card. Holding the card in place, take the cup to the sink and turn it upside down. Remove your hand from underneath. Because the water inside the cup is lighter than the air outside, the card is held in place by about 15 pounds of force from the air pushing up, while the force of the water pushing down is only about one pound of force.
Fountain Bottle. Fill a 2-liter soda bottle half full of water. Take a long straw and insert it in the mouth. Wrap a lump of clay around the straw to form a seal. Blow hard into the straw—then stand back. Your blowing increases the air pressure inside the sealed bottle.
Blow hard into the straw. As you blow air into the bottle, the air pressure increases. This higher pressure pushes on the water, which gets forced up and out the straw. Insert a ping pong ball into a funnel and blow hard.
You can tilt your head back so that the ball end points to the ceiling. Can you blow hard enough so when you invert the funnel, the ball stays inside? Can you pick up a ball from the table? As you blow into the funnel, the air where the ball sits in the funnel moves faster and generates lower air pressure than the rest of the air surrounding the ball. This means that the pressure under the ball is lower than the surrounding air which is, by comparison, a higher pressure.
This higher pressure pushes the ball back into the funnel… no matter how hard you blow or which way you hold the funnel. Heat an empty soda can large beer cans actually will work better if you have one in a skillet with a few tablespoons of water in the can over a hot stove.
When the can emits steam, grab the can with tongs and quickly invert it into the dish. The air in the can was heated, and things that are hot tend to expand. When you cool it quickly by taking it off the stove onto a cold plate, the air cools down and shrinks, creating a lower pressure inside. Since the surrounding air outside of the can is now higher, it pushes on all sides of the can and crushes it. Blow a balloon up so that it is just a bit larger than the opening of a large jam jar and can't be easily shoved in.
Light a small wad of paper towel on fire and drop it into the jar. Place the balloon on top. When the fire goes out, lift the balloon… and the jar goes with it! The air gets used up by the flame and lower the air pressure inside the jar. The surrounding air outside, now at a higher pressure than inside the jar, pushes the balloon into the jam jar.
Take an empty water or soda bottle and lay it down horizontally on a table. Carefully set a small wadded up ball of paper towel in the mouth of the bottle. The ball should be about half the size of the opening. I bet you a million dollars that you can't blow hard and get the paper to go into the bottle! Why is this so impossible?
You're trying to force more air into the bottle, but there's no room for the air already inside to go except back out the mouth of the bottle, taking the paper ball with it.
Hold a regular sheet of paper to your bottom lip you may have to play a bit to find the exact location and blow hard across the sheet. The sheet flies up! This is the same reason airplanes can fly. As you blow across the top of the sheet, you lower the air pressure because the air is moving faster , and thus the pressure on the underside of the sheet is now higher, and higher air pressure pushes the sheet upwards.
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