Oceans of Air

TOPIC: ATMOSPHERE
LEVEL: Intermediate/Advanced

"Oceans of Air"

CONCEPT:: Air is everywhere in the earth's atmosphere. It takes up space and has mass.
STUDENT OBJECTIVE:: In this activity, students will observe that air takes up space and has weight.
OVERVIEW:: In this activity student will be conducting 2 experiments to show that air has weight and takes up space. Since our atmosphere is invisible, these 2 activities will allow the student to "see" a better picture of what our atmosphere "looks like".
TEACHER TEXT:

PREPARATION TIME: 15 minutes

LESSON TIME: 30 minutes

TEACHER PREP: Gather materials, usually found in a classroom.

MATERIALS NEEDED:

STEPS TO FOLLOW:: Activity 1:; 1. Open a large sheet of newspaper and place it flat on a table.; 2. Slide a ruler under the newspaper with 8cm hanging over the edge of the table.; 3. Hit the ruler hard with your hand.; Activity 2:; 1. Blow up 2 balloons the same size and tie them- use a saucepan to measure the balloons: they are the same size when they touch the pot's sides.; 2. Tape each balloon to the end of the dowel.; 3. Balance the dowel on a pencil supported by 2 cans.; 4. Mark the balance point on the dowel.; 5. Next, put one balloon in a cold place- refrigerator, ice chest with ice.; 6. Put the other in a warm place.; 7. Let some air out of the warm balloon and blow some air into the cold balloon so that they are the same size.; 8. Balance them again.

WHY?: Activity 1:; It is difficult to lift the newspaper because of the weight pressing down on it. This weight is called air pressure and it pushes down about 14 pounds per square inch. This is called the psi.; Activity 2:; When you balance the balloons the first time, the balloons will balance equally. The temperature of the air inside the balloons is the same. When you cool 1 balloon and heat another balloon, you will notice a change. The balloons, when balanced, do not balance the same as the first. The cold balloon will lower while the warm balloon will rise. This happens because warm air is lighter or less dense than cold air. Cold air is more dense, therefore heavier.

ASSESSMENT: Can the student communicate what they observed?: 4......Student is able to communicate that air pressure pushes down on as at about 14 pounds per square inch. Student also is able to communicate that cold air is more dense than warm air which causes one balloon to rise and one to fall when balanced.; 3......Student is able to communicate that a force is pushing on the paper preventing the ruler to lift the paper. Student is also able to communicate that warm air will rise and cold air will fall.; 2......Student will communicate that the ruler is being pushed down by the paper. Student is also able to communicate that different air will make one balloon rise.; 1......Student will communicate that the ruler cannot lift the paper. Student will also communicate that one balloon was made cold and one balloon was made warm.

Last modified: Mon Aug 11 11:10:20 PDT 1997