Air Pressure

Ruthie L. Banks Carter School
5740 South Michigan Ave.
Chicago IL 60637
(312) 535-0860


Students K-8 will be able to demonstrate the pushing power, or pressure, of

Materials Needed:

Ice Cans (pop)
Funnel Bowl
Hot and Cool Water Candle
Graduated Cylinder Index Card/Flat thin card
Plastic Drink Bottle (soft) Paper Cups
Clay Coin
Glass Bottle Glass
Tissue Paper/Paper Towel


Ask students: Did you know that air presses against you at all times? Tell
them that they will see how air pushes, discover how air's pushing power,
or pressure, changes when you heat it, and find out what happens when you
reduce the air pressure inside a container. Explain and demonstrate how air
takes up space. Display the materials on the table and demonstrate the
following activities along with the students.


1. Paper Plunge: Crumple a piece of paper and push it into the bottom of a
glass. Then plunge the glass straight down into the bowl of water. Ask
the students:
1. What happens to the paper?
2. Where is the water level in the glass?
(Tell them) Water can only get into the glass by squashing/compressing the
air inside it. Air can be compressed, a little, but then it pushes back
and prevents the water from reaching the paper.

2. Cartesian Diver: Have the students observe the eye dropper. The
eye dropper will rise and sink.

(Ask them) Why the eye dropper rises and sink?

Explain that when you put the dropper in the water, air becomes trapped
inside the dropper. When you squeeze the bottle, water compresses the air
and the water takes up more space in the dropper, causing the dropper to
sink. When you relax your grip on the bottle the air in the dropper top
expands again causing the water to be pushed out of the eye dropper. Then
the dropper floats back to the surface.

3. Jumping Coin: First smear some cold water over the coin and over the top of
the bottle. This will make an airtight seal when you rest the coin on top
of the bottle. Hold your hands around the bottle and wait for about 30
seconds. What happens to the coin? Take your hands off the bottle and wait
again. What happens to the coin now?

4. Sticking Together: Cut a 1.5 cm hole in the middle of the blotting paper,
then wet it thoroughly. Put a small amount of clay into the paper cup.
Stand a candle in the paper cup. Tip the cup and light the candle. Quickly
cover the cup with the wet blotting paper. Then stand the second cup
upside-down on the top of the first cup, making sure that it fits exactly
over the first cup. Wait until the flame goes out (about 20 seconds). Then
lift the top cup gently. If you have matched their rims exactly, the cups
should stick.

5. Crushing With Air: Activity 1 (Bottle)
Stand the bottle upright in a bowl. Pour the hot water into it and leave it
for a short time. Screw the top on the bottle. Lay the bottle in the bowl
and pour ice cold water over it. Then stand the bottle up.

Activity 2 (Can)
Pour a small amount of water about (5 ml) into the can. Heat gently over
candle. When water begins to boil and steam rises from the can, remove from
the heat. Quickly place the can upside down in the bowl of water.
(Answer) The can/bottle retains it shape in a normal atmospheric condition,
because the air pressure inside the can/bottle is the same as the air
pressure outside. The can/bottle collapse as the warm air inside the
can/bottle cools, it exerts less pressure. The pressure of the air outside
is stronger and crushes the bottle/can. (Ask students)

1. What happened?
2. Which is stronger the pressure of the air outside
or inside the bottle/can?
3. What made the bottle/can crush?

6. Seal With Air: Hold the glass over a bowl. Carefully pour some water into
the glass. Place the card on the glass. Hold it down so the card touches
the rim all the way around. Still holding the card, turn glass upside down.
Let go of the card. What happens? (The water stays in the glass!)

Performance Assessment:

After completing these activities students will be able to demonstrate various
concepts about air; air exists, air has volume, air exerts pressure, hot air
rises, and cold air has lower pressure than hot air.
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