Purpose: To show the need to put into practice what we learn.

Materials: A whistle.

Lesson: There are many different kinds of whistles, but they all work in the same way. You take a deep breath and blow the air into the stem of the whistle, like this. (Blow the whistle, but keep your finger over the top opening.) What happened? No sound came forth from the whistle. Oh, I see. I had my finger over the opening here and, therefore, the air could not go through, no matter how hard I blew.

This shows us an important basic rule…