Materials List: plastic rulers, balloons, hand air pumps (optional), science learning logs, Science Learning Log Recording Sheet BLM (see Activity 2), Science Learning Log Rubric BLM (see activity 2), photos of musical instruments
This activity may take two days to complete.
Nearly every sound you hear is made by something vibrating. All things that make a sound do so by making the air shake back and forth very quickly. This shaking is called vibration. These vibrations travel as sound waves. Although we cannot see sound waves, we can sometimes see the vibrations that make the sounds.
Investigation Task: Ask the question, “What would happen if you bent a ruler over the edge of your desk, held down one end, pushed down the other end and then let it go?” (You may want to demonstrate the position without causing the vibrations.)
Give students time to voice predictions without responding to them. Next give out rulers for student exploration of vibrations. Remind students of safety procedures and ruler etiquette.
As students explore, engage them with questions such as, “What happens to the sound when more or less of the ruler is hanging over the edge of the desk?” As students begin to discuss the sounds, introduce the term pitch to describe the highness or lowness of the sound.
Next have students explore how to make sounds using the balloons. If manual air pumps are not available, students will need to blow the balloons up by mouth. Remind students of safety issues related to not sharing balloons blown up by mouth and of blowing the balloons up too much. Students will eventually begin to hold the neck of the balloons and pull to let the air out causing a “raspberry” sound. Let volunteers suggest what is creating the sound that comes from the balloon (see How It Works!). Invite students to tighten or loosen their hold on the neck of the balloon to see how many different sounds they can make. Introduce the term pitch which refers to the highness or lowness of a sound. Have students explore how to make higher and lower pitched sounds with the balloons. Engage students in a discussion of familiar musical instruments. Have students suggest how each produces vibrations to create sound waves.
Have students describe the activity in their science learning logs (view literacy strategy descriptions) including an explanation of how the “raspberry” sound was created. Students can write freely in their science learning logs or use the optional Science Learning Log Recording Sheet BLM provided. An assessment rubric for science learning log entries is provided as the Science Learning Log Rubric BLM.
How It Works!
As the air escapes from the balloon, the neck of the balloon vibrates causing the “raspberry” sound.
Fantasia DVD/Video – There is a wonderful sequence showing vibrations as different instruments are played.