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Air Pressure -Keep paper dry under water! (Sabiha Dalal)

Author

Sabiha Dalal, 6th grade Special Education Teacher, Sepulveda MS

Principle(s) Illustrated

  1. Air Pressure

Standards

  • 1.1.1 - Science Standard - Chemistry Grades 9-12
  • Gases and Their Properties
    • The kinetic molecular theory describes the motion of atoms and molecules and explains the properties of gases. As a basis for understanding this concept:
    • a.) Students know the random motion of molecules and their collisions with a surface create          the observable pressure on that surface. 
    • b.) Students know how to apply the gas laws to relations between the pressure, temperature, and volume of any amount of an ideal gas or any mixture of ideal gases. 
  • Investigation and Experimentation
    • Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will:
    • b.)Develop a testable question
    • h.) Draw conclusions from scientific evidence and indicate whether further information is needed to support a specific conclusion. 

Questioning Script

          Materials:

            1.) Large clear container, 2/3 full with water.
            2.) Beaker or clear glass/plastic cup.
            3.) Colored paper or tissue paper

          Procedure: 
            
            1.) Crumple a piece of the tissue paper and stuff it inside the cup or beaker.
            2.) Place the beaker or cup open side first, into the container of water.
            3.) Observe what happens.
            4.) Remove the cup from the container of water and determine if the tissue is dry or wet.
            5.) You can do this again keeping the cup at an angle in the water and your results will change. 
            

Prior knowledge & experience:

Students know that air is a gas. They have experienced that when things are submerged in water they get wet. 

Root question:

What will happen to the tissue or paper once submerged in water?

Target response:

By the end of this activity students will understand that air does take up space even though you may not be able to see it. Air molecules are constantly bumping and moving around. Air molecules inside a glass are constantly bumping into each other and this causes pressure. In this activity, air molecules are also bumping into the surface of the water. This creates enough pressure to keep the water out of the glass. The air molecules are creating a wall that keeps the water out. This is why the tissue remains dry. 

Common Misconceptions:

A common misconception from students is that air is invisible and does not take up space. When you immerse something in water it will become wet.

Photographs and Movies

 

Demo Video

References

Fluid pressure and depth

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Sabiha Dalal,
Oct 12, 2011, 4:32 PM
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