## IF YOU'RE UNDER PRESSURE, BLAME IT ON THE AIR FORCE Grades 3-6

Air is all around us, and is necessary for our survival on earth. This lesson allows the students to investigate the idea that air is not just something that we breathe, but a powerful force that is all around us. The students will learn that air is pushing constantly in every direction; up, down, and sideways. They will also learn that air can do work. This activity allows the students to do experiments, collect data, make charts and graphs, and interpret their findings.
Science For You #6: How Heavy Is Air?
The Science Alliance #7: Air
Take a Look 2 #1: Air Pressure
Students will be able to:
• demonstrate that air exerts a force
• define air pressure
• construct a siphon
• estimate the time it will take to siphon different amounts water; and collect, chart, and analyze data
Can Crushing Demonstration:
• 1 aquarium or other large container
• 6 empty soda cans
• ice cold water (enough to fill aquarium)
• 1 pair tongs
• 1 hot plate
Siphon Activity Per group or four students:
• 1 one-liter bottle (empty)
• 1 one-liter bottle (filled with water)
Note: both bottles should have markings of 1/4L, 1/2L, 3/4L, and 1L 1 piece plastic tubing (1/4 inch by 4 feet)
• 1 piece plastic tubing (1/8 inch by 4 feet)
• 1 stopwatch
Place about one-half inch of water into an empty soda can. Tell the students to observe the can. Put the can on the hot plate and heat it until you see steam coming out of it. Ask the students what they observe. Elicit responses. Using tongs, grasp the can, quickly invert the can, and put it into the cold water. (The can should be as vertical as possible and placed into the cold water about one half of an inch deep.) The students will hear and see the can crush. This activity dramatically shows the students how powerful the air is, and should be repeated a couple of times. Ask the students why the can was crushed when it was placed in the cold water. Elicit responses.
The focus for viewing is a specific responsibility or task(s) students are responsible for during or after watching the video to focus and engage students' viewing attention. Tell the students that they are going to view three video segments that will help them understand why the can crushed.

Tell them that in the first segment they will watch a similar can crushing experiment, and that they should be able to answer the following questions: What happens to the air in the can as it is being heated? What evidence did you see? Does air have weight? How much weight does it exert? Why did the can crush?

In the second segment, the students will watch an experiment, first without sound and then with sound. Tell the students that they are to determine why the water doesn't come out of the glass jar. Inform the students that the first two segments will help them apply their knowledge of air pressure in a different situation. When they finish watching the third segment, they should be able to explain what a siphon is and how it works.

BEGIN the video Science for You #6: How Heavy Is Air? when you see a can on its side with the words "Experiment: Air Has Pressure." PAUSE when you first see steam coming out of the can. Have the students describe the similarities between what they saw in the video and what they saw in the earlier demonstration. Elicit responses.

RESUME the video and PAUSE when the can is put into the water. Ask the students if they know what is going to happen to the can and why. Elicit responses.

RESUME the video and PAUSE when three yellow arrows are drawn around the can. Ask the students if they think more arrows should be drawn to help explain what is happening. With a water soluble marker, have a volunteer draw three more arrows on the television screen. Ask them what the arrows represent. Discuss how they represent the air pushing in all directions. Erase the arrows from the television.

RESUME the video and STOP when you see a map of the earth and the narrator says "That's pretty heavy." Ask the students how much weight air exerts. Discuss responses. Review how the can was crushed by the air.

BEGIN the video The Science Alliance #7: Air when you see a lady holding a green ball saying "I'm pressing on a foam ball." PAUSE the video when she turns a flask upside down, holding a note card to the opening. Ask the students what they think will happen when she moves her hand away from the note card. Elicit responses.

RESUME the video and STOP when she pulls the note card from the opening and lets the water out. Ask the following questions. Did the card fall off when the flask was upside down? When it was sideways? Why didn't it fall off? Elicit responses and discuss.

BEGIN the video Take A Look 2 #1: Air Pressure when Kate and Jeff are sitting at a table and Kate says "Now let's go to my workshop and I'll show you a way to move water around where you don't have to use so much energy." PAUSE the video when Kate and Jeff are in the workshop and she says,"This is a siphon." Ask if anyone knows what a siphon is, and if anyone has used a siphon. Elicit responses and discuss.

RESUME the video and STOP when Kate says, "And letting air pressure do the work for you." Ask the following questions: What work was being done? What did the work? Who can explain what a siphon is and how it works?
In the last video, the students saw how a siphon is made and how it works. The assignment is to make a working siphon and calculate how long it takes for the water to move from one bottle to the other. The experiment will be done twice. First, the students will use the 1/8" by 4' piece of tubing to determine how long it takes to fill the bottle on the floor 1/4 full, 1/2 full, 3/4 full and 1 full liter. Then, the students will repeat the experiment using the 1/4" by 4' piece of tubing.

Note: Make estimates before doing the actual timings. Take some time to "play around" with the siphons to make sure that you understand how they work. Once you feel comfortable with your siphon, do the experiment and fill out the worksheet.
Have a local farmer visit the class to discuss how he uses siphons to irrigate his fields.

Invite a city engineer to class to discuss how the water systems and sewage treatment plants work.

Have a plumber visit the class and discuss how plumbing in your homes work. He can also bring in various pumps to show the class.

Invite a meteorologist to class to discuss how air pressure is related to our daily weather.

Visit a gardening store that sells pumps for garden ponds.
Social Studies and English: Have the students research and write papers on ancient civilizations and how people irrigated their farmland.

Science and Art: Using battery-operated pumps, have the students make their own miniature water gardens.

Science and English: Have the students build a model of a reservoir and make class presentations with them.

Science and Math: Using small electric pumps (like those used to drain waterbeds), have the students calculate the number of gallons each pump circulates in a minute, for every ten minutes, per hour.

Math: Have a contest where the students have to figure out how long it will take to drain an aquarium using different amounts and different sized tubing.