## AIR: IT'S A GAS! Grades 4 - 6

This lesson will introduce the properties of air through hands on activities in conjunction with the demonstrations in a 3-2-1 Contact Video. Students will both see and experience concrete examples of these properties. In particular, this lesson will focus on the concepts of air being matter, having mass, occupying space and its ability to exert force or pressure.
"3-2-1 Classroom Contact, "Air is Matter: Air is There"
Students will be able to:
• demonstrate that air can exert pressure or a force.
• observe that air has mass and weight.
• observe that air occupies space.
• 2 Mylar air tubes.
• 1 Hot plate.
• empty aluminum Orange Slice pop can.
• 1 empty aluminum pop can (any brand), for each student.
• Clear plastic container, 1 to 3 gallon capacity filled to within an inch or two of the top. A few ice cubes would be nice.
• 2 Pair metal salad tongs.
• 2 Identical folding tables, 3'x 6'.
• 1 Open test tube or jar full of air.
• Several photographs of sailboats or sailing ships with their sails full of wind.

each student
• Paper and pencil
Properties: A particular quality of anything:, that which is inherent in a thing.
Matter: That which occupies space and can be known to us by our senses.
Mass: A measure in the amount matter that makes up an object.
Pressure: The condition of a fluid such that it exerts a force on a surface in contact with it. Pressure = force / area.
Force: That which tends to change an object's inertia.
Weight: The force by which a mass is attracted by the Earth. / That force which a body exert on its support when at rest.
Volume: A measure of the space occupied by an object.
Fluid: A substance that flows; i.e. a liquid or a gas.
Standing before the students, hold the test tube or jar upside down, shake it and ask, "What do I have in this test tube?" If a number of students respond, "nothing," then ask everyone in the class to take a deep breath, (joining in yourself of course) and then exhale. What did we just inhale?" (atmosphere, air). "And what's in our air that allows us to live and breathe?" (oxygen).

Ask the students if they can name some of the properties of air. Write them on the board. In addition to being invisible and odorless, see how many of the properties of air as listed in the vocabulary they can come up with. For those properties that they don't offer ask (for example)... "Does air have weight? Does air have mass? etc."

If the class cannot come to a consensus or if there is some strong dissension as to whether air has any of these or other properties offered by students, do not force a conclusion. Leave the question open ended for the time being. Hold the test tube or jar upside down and say, "So, we can't see air, but how do we know it's there? How does this invisible thing called air make its presence known to us? And as invisible as air is, how do we make use of it every day?" (Give students time to respond and share ideas).\

Set up a 3' x 6' folding table. Be sure to have found by use of a bathroom or school infirmary scale the approximate weight of the table before hand. Place an identical table with legs folded face down on the first table. Sit on the second table facing the class and say,"The folded table I'm sitting on weighs about [ X ] pounds. I weigh, (and this is the toughest part) [ Y ] pounds. So how much does the top table and I weigh together?" (The easy "weigh" out is to tell your students that you and the table together weigh [ Z ] pounds. If I were to find something to lift this top table with me sitting on it, would it have to have mass?" (Yes)

"Would that 'something' have to be able to provide pressure to lift us?" (Yes)

"Would that 'something' have to be able to apply force to lift us?" (Yes)

"Would that 'something' have to be made of matter?" (Yes)

"Would that 'something' have to have weight?" (Yes)

"Would that 'something' have to have volume?" (Yes)

"We'll return to these tables when we find the right 'something' that has all these properties."
Holding the test tube or jar up side down say, "Air, pretty important stuff for something you can't even see." To give students a specific responsibility for viewing say, "We are about to watch a video which will deal with the properties of air. As we watch the first section of the video, make a note of the properties it identifies. Does it mention any properties we've listed? Does it mention any additional properties? Also, take note of what evidence air gives to make its presence known and some ways we use the properties of air for our benefit."

BEGIN the tape with the title frame, "AIR IS THERE, AIR IS MATTER," which follows immediately after the 3-2-1 Contact theme. PAUSE tape immediately after Kenneth says, " Air is real stuff. It has mass and volume just like you."

Compare the class' list of properties with the ones provided by the video. Have students think of examples. Key words and concepts provided by the video selection: can hear it, can't see it, blows things around, can feel it, fun, can travel on it, has weight, takes up space, has mass, volume, a predictable behavior, its a fluid, and it flows. The final three ideas predictably, will give some students the greatest difficulty. To provide some illumination on these last three concepts, direct the discussion toward the topics of air currents and water currents, warm fronts and cold fronts, rising warm air, descending cold air and, how does a weatherman predict the weather.

"We're now going to return to the video where Kenneth will be giving us a couple of interesting demonstrations on some of the properties of air we've been discussing."

RESUME Tape: After Kenneth says, "I turn the cup upside down and place it into this handy tank of water, PAUSE the tape. Ask... "What do you think will happen to the dry tissue in the cup? Why?" Students should at this point be able to explain that the tissue will remain dry since there is air already in the cup. If not, have them review the properties of air and lead them in a discussion that will help them see what is happening.

RESUME Tape to verify student responses. Continue showing the first part of Kenneth's next demonstration. When Kenneth say's, "I let the air out of one of the tanks..." PAUSE The Tape immediately. Ask... What do you think is going to happen? (Tank with air loss will get lighter and will rise on the balance beam) Explain your predictions in terms of the properties we've discussed.

RESUME Tape to verify predictions and answers. Continue until end of demonstration.
Right after Kenneth says, "I still hear lingering doubts. Some of you are tough. O.K., take a look at this", PAUSE The Tape.

Hold up several pictures of sailing ships with their sails full. Say... "Take a look at these sailing ships. Discussion: What is powering them? (moving air, the wind) "What would happen if the wind stopped blowing? What would the sails look like then? So what is it that gives shape to the sails?" (air)

"We usually think of things being powered by moving air as old fashioned. Most ships or boats we find powered by wind today are usually for sport or recreation."

"As we watch this next segment of our video, make note of how the properties of air that we usually associate with sailboats are put to a very modern and surprising application. Also,we can't always rely on nature to provide wind when we need it. See if there is any mention of how modern man makes his own wind."

RESUME Tape. When the daughter says, "One of his roofs are going to be inflated today", PAUSE the tape immediately so that the picture of the uninflated stadium roof is frozen on the screen.

"Did anybody catch the name of the young lady? "(Karma). Discussion: What's special about what her father does? What do the roofs that her father builds have in common with the sails on boats?" Have the students focus their attention on the stilled video picture of the stadium with the uninflated roof. Ask... "What is there about the uninflated roof on this building that might remind you about the sails on a boat". The students may have numerous good responses but eventually guide the discussion to the idea, (if no child volunteers it on their own) that the uninflated roof is very much like the sail on a boat when the wind is no longer blowing.

" How many of you would like to walk on a roof made like a sail? How many of you think you can walk on a roof made like a sail? We're now going to get a closeup look of this sail-like roof that will probably answer a bunch of questions you might have about it. What kind of fabric is it made out of? How strong is it? How big is it? How light or how heavy is it? Can you actually walk on it or would you fall through? To find out some of these answers you will need to listen to the conversation between Karma and her Dad. You will also need paper and pencil ready to jot down numbers and do some calculations."

RESUME Tape. To allow the students to review what they've just learned about the roof and to calculate its weight, PAUSE tape immediately after Karma's father says, "Pound per square foot" in his statement, "...but if you have 400,000 square feet and you add the cables and clamps and the roof weighs a pound per square foot..."

"How big is this fabric roof? " (ten acres, five football fields, or 400,000 square feet)

"How much does the fabric itself weigh per square foot?" (About 1/4 pound ). "Do you think that would be considered heavy or light for a roof? ." For older classes that can multiply fractions ask... "How much does the fabric for the entire roof weigh?" (100,000 pounds). You might ask the children to consider what goes into the roof of a house, (Shingle, roofing felt, nails, 3/4 inch plywood, 2"x6" wood beams) and how that would compare with the weight of a fabric roof.

"If you add the weight of the cables and the clamps, how much will the roof weigh per square foot? " (one pound). "At one pound per square foot, how much will a 400,000 square foot roof weigh?" (400,000 lbs.)

"How many automobiles do you think it would take to equal 400,000 pounds?" (record answers on the board).

What is the fabric made of (Teflon coated fiberglass) and how strong is it?" (Very strong!) "Is it safe to walk on a fabric roof of this kind? (walk, jump, and slide!). "I now think we all have a better idea of what this fabric roof is all about. And of course since the beginning of the video the fabric roof has been constantly compared to a what?" (the sail on a boat).

Hold up a picture of a sailboat. "Now we've seen several pictures of sails full of wind, so I think it's about time to see what a fabric roof looks like full of air. But if a sail gets its air pressure from the wind, where does a roof get its air pressure from? Does anyone remember what was said earlier about how they inflate the roof? " (fans).

To verify the students' previous responses pertaining to total roof weight, its equivalent weight in automobiles, and how a fabric roof is filled with man made wind say: "Let's return to our video and see not only how they raise the roof but just how long it takes and how high it gets." RESUME Tape.

After Karma's father says, "That's the height of a 20 story building", STOP The Tape. DISCUSSION: Did we come up with the correct total weight of the roof, (400,000 lbs.). Did anyone guess the correct equivalent weight in automobiles? (about 15 cars). What height did it reach and in what length of time? (200 feet or 20 stories, and in 2 to three hours). And where does a fabric roof get its air pressure from? (fans).

After the end of the discussion, FAST FORWARD the tape through the next demonstration.

When you see Kenneth place the second potato on the end of a clear plastic tube for the second time, PAUSE The Tape and MUTE, immediately before the video advances into the next demonstration.

"In the next demonstration we shall clearly see that air has mass, weight, and pressure. We're going to watch Kenneth do another demonstration but this time we're going to ask the questions and provide the dialog."

RESUME Tape and allow it to play until Kenneth has put both hot mitts on, then PAUSE.

Discussion: "What is the metal can sitting on? (a stove or hot plate). "What is happening to the air inside the can as it sits on the hot burner?" (it's getting hotter). "What happens to air when it gets hotter?" (It gets more active, it can expand)

RESUME the Tape and continue playing until camera shot pans in for a closeup of the metal can, then PAUSE The Tape for discussion.

"What do we see coming out of the open spout of the metal can?" (air) "Where is there greater air pressure, on the inside of the can or on the outside?" (on the inside but constantly trying to equalize). "If the inside of the can is loosing air, where can it get energy from to equal or surpass the air pressure on the outside of the can?" (The heat from the stove). "So the air on the inside of the can has lost mass but gained heat. Is heat a form of energy?" (yes)

RESUME The Tape and play until Kenneth is seen sealing the can with a cap and removing the can from the stove.

As soon as Kenneth sets the can on the table, PAUSE the tape so the students can discuss and predict what is going to happen and why.

After the class has agreed on one or more theories, RESUME The Tape until the can is seen to crush. Immediately PAUSE the tape. Have students discuss if what they just saw verifies or contradicts what they predicted. Let the students reform and restate theories if necessary.

In order to verify their ideas, Remove Mute, RESUME The Tape. The video should start out with Kenneth saying, "What smashed the can? Air, the air all around it." Have Kenneth complete his explication

When he completes his explication by concluding, "Air pressure crushed the can. Air in action!" Immediately STOP The Tape. Have students discuss Kenneth's explication and how it fit with their theories and explications. In conclusion, focus on statement made by Kenneth, "When I heated and sealed the can very little air was left inside. Too little air to stand up to all the pushing in on it. "

Return to the two folding tables. Say, "Earlier I mentioned that in order to lift this table top with me on it, I needed something that has mass and can provide both pressure and force. It must be made of matter and have weight and volume. Does air fit this description?" (yes)

"Let's see if we actually can make air lift this table."

Remove the top table. Tie a knot at the end of two Windbags and spread them both lengthwise and flat across the bottom table. The two ends of the Windbags should hang out from both ends of the table. Have several students assist you in carefully aligning the second folding table on top of the first (see illustration). Put four students, one at each corner of the table to spot the top table from rolling or shifting. Sit yourself down in the middle of the top table. Have two students kneel at either end of the table. Instruct them to blow into the open ends of their Windbags and to tightly squeeze the open end closed after each breath so as not to let any air escape. The inverted table and the person (or persons) sitting on it will all slowly begin to rise. Note: make sure everyone working around the table knows not to put hands or fingers between the two tables.

Ask (from your newly elevated position in life)... "What is lifting the weight of both you and the table?" (air pressure) Direct everyone's attention to the shape of the air tubes. "Does air appear to have mass, force and pressure? (Yes!) Does air have volume and weight, and is it made of matter? (Yes!) Then as the video states, air must really be there."

Optional Post- Viewing Activity:

(Or How To Make Orange Crush From Orange Slice) Turn a hot plate on up to high. Fill an empty pop can (preferably an Orange Slice can for the first demonstration) with about 1/8 inch of water, just enough to cover the bottom of the can. Place the can on the hot plate. Ask... "Is the air inside gaining heat or loosing heat." (gaining) "Let's predict. As the air inside gains heat energy, what is it going to do?" (become more active, expand, escape from the can). Steam and water vapor will shortly start raising from the can, pushing air out.

"Heat is a form of energy which makes air become active and expand. What is the opposite of heat?" (cold) "Do you see anything on this table which could take away some of the heat from both this can and the air inside?" A clear plastic container with cold water and a few ice cubes floating around for a visual effect should be conveniently set on the table. Have a student volunteer come up and with a pair of metal salad tongs, clasp the can and quickly invert the can top down into the cold water. The top needs to be immersed only a quarter inch or so and not submerged deep into the container in order to make the demonstration work. It is best to demonstrate the technique to the children first with an unheated can and let the first student volunteer do the same before attempting the real thing.

Almost instantly the Orange Slice can should implode (which as everyone knows, makes Orange Crush). This is a good demonstration to get the whole class to participate in as three or four pop cans can sit on the hot plate burner at a time.

Ask the students to explain what happened during the demonstration. Again, as in the demonstration Kenneth provided in the video showed, heating the can and its contents meant a loss of mass. But adding heat to the remaining air mass allowed it to keep enough pressure to sustain the shape of the can. By quickly inverting the can in cold water its contents suddenly had neither the mass nor the energy to provide pressure enough to counterbalance the pressure on the outside of the can. And as Kenneth stated, "When I heated and sealed the can (whether it be with a cap or the surface of the water) very little was left inside. Too little to stand up to all the air pushing in on it. Air pressure crushed the can. Air in Action."

Have a local television weather person visit your school to show and explain how the properties of air you have been studying manifest themselves in the daily forecast and interpretation of the weather. Better yet, visit the T.V. or weather station.

Have a hot air balloon inflated on your school field. Have them explain those same properties of air as it pertains to inflating , flying , and navigating a hot air balloon. Contact balloon clubs or some of the broadcast stations and private industries that advertise themselves on hot air balloons.
Music
Research how wind instruments use the properties of air to make sound, the different tones and, all the different notes.

Mathematics
Instead of how many cars it would take to equal the weight of a 400,000 pound fabric roof, figure it out in terms of elephants, a favorite dinosaur, boxes of Captain Crunch, or hamsters.

If air weighs 14.7 pounds per square inch at sea level, find the area of a pop can and figure how much total pressure was responsible for making the can collapse.

Science
Find out what the air pressures are on different planets in our solar system. What would be the effects on an unprotected space traveler used to 14.7 p.s.i. on these planets?

How are spacesuits designed compensate lack of air pressure in space or on the moon?

Why do your ears feel so funny in airplanes or while driving up into or down out of the mountains?

Have students use party balloons to lift textbooks and other objects on their desks. Be sure students weigh the objects they lift.

Resources:

WINDBAGS can be purchased through ;

WREN Enterprises, Inc.
3145 West Monmouth Ave.

333 Science Tricks and Experiments
Robert J. Brown
TAB Books, Division of Mc Graw-Hill, Inc.
Blue Ridge Summit, PA. 17294-0850

333 More Science Tricks and Experiments
Robert J. Brown
TAB Books, Division of Mc Graw-Hill, Inc.
Blue Ridge Summit, PA. 17294-0850

New Unesco Source Book for Science Teaching
United Nations Educational, Scientific and Cultural Organization

Robert C. Mebane &Thomas R. Rybolt
Enslow Publishers, Inc.
Hillside, N.J. 07205

Adventures With Atoms and Molecules, II
Robert C. Mebane & Thomas R. Rybolt
Enslow Publishers, Inc.
Hillside, N.J. 07205

How Science Works