Tissue In Glass

TOPIC: Principles of Flight: Air
LEVEL: Beginner

"Tissue In Glass"

SCIENCE CONCEPT:: Air is a gas which is a form of matter. Air takes up space.
STUDENT OBJECTIVE:: The student will discover two objects cannot occupy the same space.
OVERVIEW:: The student will experiment to see that air trapped in a space fills the entire space and will not let water into the occupied space. Question: Can 2 people stand in the same place at the same time? (No. Have children try. They will discover they must shove the other person out of the way to stand in the same place.)
TEACHER TEXT:

PREPARATION TIME: 5 minutes

LESSON TIME: 10 - 45 minutes, depending upon time allotted for group investigation

TEACHER PREP:

WORDS TO KNOW:

STEPS TO FOLLOW:: 1. Fill the tub with water.; 2. Push a tissue into the glass making sure it is to the bottom.; 3. Invert the glass. Make sure the tissue stays in place.; 4. Submerge the inverted glass with tissue inside into the water, keeping it perfectly straight up and down.; 5. Lift the glass out of the water. Examine the tissue.; 6. Repeat.

WHY?: Although it is invisible, air occupies the space inside the cup. Water cannot get into the same space so the tissue remains dry.

ASSESSMENT: Can the student communicate what they observed?: 4 . . . . The student is able to communicate that two objects cannot occupy the same space.; 3 . . . . The student is able to communicate that air fills up the glass.; 2 . . . . The student is able to communicate that something is keeping the tissue dry.; 1 . . . . The student is able to communicate that the tissue doesn't get wet.

EXTENSIONS:: 1. Repeat the experiment. This time tip the glass while it is under water. Observe. Now remove the glass and examine the tissue. Is it dry? Why not? (The tissue will be wet because tipping the glass allowed the air to escape; therefore, the space was empty, allowing the water to get in.); 2. Use a glass with a hole in the bottom. ( Teacher prepares the glass ahead of time. A small hole can be made by holding the clear plastic glass over a match flame. The plastic melts very quickly.) What happens to the tissue? (It gets wet because the air escapes out of the hole leaving space for the water.) A few drops of food coloring in the water makes this easier to see. Have the children compare the glasses - what's different? (hole); 3. Using a dry, empty glass with a hole in the bottom, place a small square of tissue on top of the inverted glass over the hole and quickly submerge the glass. Observe. (As the glass is submerged, the force of the escaping air will will push the tissue up.This is very visual and the children can see where the air is going.)

Last modified: Mon Aug 11 11:53:15 PDT 1997