Cover a large glass bowl with cling film and place a few grains of sugar on top. Bang a large baking tray with a wooden spoon near to the bowl. What happens to the sugar? This demonstrates that sound waves travel through the air and make objects vibrate. When you bang the tin, it causes the particles of air around it to vibrate. This is turn makes the cling film vibrate which makes the sugar jump showing the ability of sound waves to travel through air and other objects.
Take a ruler and hold it so that most of it is hanging over the edge of a table. Now twang it. Pull the ruler in slightly so that there is less of an overhang. Twang it again. Does the pitch get higher or lower?