Subject: Science 

Topic: How Does Sound Travel? 

Outcomes: Students will understand sound waves are compression waves. 

Background:  The sounds you make are compressing and expanding the air around you.  This compression and expansion produce vibrations in molecules of air.  An accordion type of motion continues through the air because each air molecule collides with the one next to it and starts it moving in the same direction.  The alternating compression and expansion of the air molecules produces a sound wave. 

Learning Activities: 1.  Marble Model - Spread out five marbles in a line between two metre sticks that have been taped to a desk.  Roll the end marble into the one next in line and observe what happens.

2. Skipping Rope Model - Have two students hold a skipping rope taught between them.  One student snaps their wrist to start a wave in the rope that travels to the other person.  Frequency and amplitude of the snaps demonstrate changes in characteristics of a sound wave.

3. Slinky Model – Have two students stretch a slinky between them.  One student quickly pushes their end of the slinky toward their partner to cause a “wave” that travels the length of the slinky.

Evaluation: After trying each of these demonstrations have students draw a picture of one of the activities and write a brief description of what was observed answering the questions:  What represented the sound travelling through the air?  Where did you see compression?  Where did you see expansion?

Reference:  NetWorks – Understanding Telecommunications, Networks Implementation Guide, produced by Science Alberta Foundation