The Straw Instrument
Emily Jacobs

Materials:
1. reeds and mouthpieces from various instruments (for demonstration)
2. straight straws
3. scissors

Estimated Lesson Time:
15-20 minutes

Procedure:
1. Begin by asking for a definition of sound (vibrations).
2. Discuss the way that vibrations are made with pressure (see diagram below).
3. Discuss and explain the different ways that the various instruments create vibrations (see diagrams below).
4. Demonstrate the different reeds and mouthpieces to show the vibrations.
5. Flatten the straight straw at one end and cut the end to a point (see diagram below).
6. Place the straw in your mouth with your lips firmly gripping the end and blow.
7. Discuss the reason why this sound is made.
8. Suggest different ways to change the pitch of the straw instrument (i.e. the straw trombone, straw oboe).

Physical Explanation:
The air is pushed through the reed, which increases the speed of the air between the reeds. This causes the air pressure inside the reeds to decrease. The air pressure in the players mouth is still either equal or slightly higher than atmospheric pressure. This difference in air pressure pushes the two reeds together, which stops the flow of the air through the reeds. Once the air flow stops, however, the air pressure rises to the original inside the reeds. Because the air pressures outside and inside the reeds are now equal, the two reeds open again (its equilibrium position). This process repeats itself over and over, creating the vibrations which we hear as the sound of the instrument.
This should picture the physics behind a vibration.
Vibrations
This pictures the double reed.
Double Reeds


This should picture a clarinet mouthpiece.
Single Reeds 

This should picture a flute head.
Flutes


Citations:
Zook, Alma C. The Physics of Woodwinds Collapse . 2006. 24 Feb. 2007 <http://www.brookscole.com/physics_d/templates/student_resources/003026961X_serway/optional/woodwinds.html>.

Sabbeth, Alex. How Wind Instruments Make Sounds. 1998. 24 Feb. 2007 <http://members.aol.com/Alsabbeth/Wind.html>.

Institute of Physics. Straw Oboes. 2006. 24 Feb. 2007 <http://www.physics.org/hostedpages/physicstogo/trick_03.asp>.