The Nature of Sound with a Slinky

Kyle Johnson, Jordan Elementary School, Jordan, MN, based on the Macmillan McGraw-Hill 4th Grade Textbook, Unit F- Energy, Lesson 5 Sound.
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Summary

In this physics classroom lesson, students investigate how sound can be produced and changed. Students identify vibrations as the source of sound and how it can be amplified and received. Students also explore the use of a slinky to explain the nature of a wave and how a sound wave is similar to the slinky action.

Learning Goals

This activity is designed for students to explore how sounds can be produced and changed, identify vibrations as the source of sound, and compare the pitches, volumes and intensities of sound. Students will also be able to describe how the structure of ear enables it to receive and transmit sound and how it can be amplified.
Vocabulary:
-Vibrations
-Medium
-Sound wave
-Frequency
-Pitch
-Amplitude

Context for Use

This activity should take 3-4 days of 45-50 minutes per class to cover the objectives of sound. A group of 4 students working together on the experiments with the slinky and questions to follow would be appropriate for this lesson. A classroom of 24 students would be ideal, if we taught in one of those settings. Teachers can make it work with any number of students or as a demonstration for total class. A slinky per group is required to do this project, tape, recording material. This activity follows the Minnesota State Standards and is part of our curriculum in our school. The prior knowledge of students should include a background on how light works, which is the chapter before sound in our textbook.

Description and Teaching Materials

Sound and music are parts of our everyday sensory experience. As humans we are equipped with ears for the detection of sound. Sound is a wave, which is created by vibrating objects and moved through a medium from one location to another. A wave can be described as a disturbance that travels through a medium, which transports energy from one location to another location. The medium is simply the material through which the disturbance is moving; it can be thought of as a series of interacting particles. We are going to use the slinky to illustrate the nature of a wave. A disturbance is created within the slinky by the back and forth movement of the first coil of the slinky. The first coil becomes disturbed and begins to push or pull on the second coil. This push or pull on the second coil will displace the second coil from its position. The second coil moves the third coil and so on. Subsequently the disturbance travels through the slinky. A sound wave is similar in nature to a slinky wave in there is medium which carries the disturbance from one location to another. Air is the medium in this activity, but water or steel could also work. Since air molecules are moving in a direction which is parallel to the direction which the wave moves, the sound wave is referred to as a longitudinal wave. Regardless of the source of the sound wave- guitar, voice, clap, rubber band- sound waves traveling through air are longitudinal waves. Students with their slinky can create a wave length. Like all waves, a sound wave has a frequency. A frequency is the number of times a sound source vibrates in one second. Tighten and loosen the slinky to change the frequency. Frequency determines pitch. Pitch is the highness or lowness of sound. Create a low frequency wave with a slinky by moving it slowly, and create a high frequency wave by moving it rapidly. Amplitude is the energy in a sound wave. Students can try to simulate what high and low amplitude waves look like with their slinky. High amplitude sounds are made by objects that vibrate with a lot of energy, like the sound of rocket blasting off. Low amplitude waves are like a whisper, where your vocal cords vibrate lightly to make sound waves. In conclusion students would relate sound waves to our ear and how the human ear hears.
www.exploratorium.edu/snacks/index.html and Macmillan McGraw-Hill 4th Grade Textbook, Unit F- Energy, Lesson 5 Sound.

Teaching Notes and Tips

Guided practice with the slinky after the first experiment might be helpful to the students to make sure they are seeing the correct wave lengths. Another suggestion would be to give students a clear set of guild lines to follow on the use of the slinky, because slinky springs could be flying everywhere.

Assessment

I would test students on what is sound, what makes sound, and how does sound travel. How do different musical instruments make sound and which sound waves have more amplitude? These questions are used to assess what the students have learned in the hands-on activity using a slinky.

Standards

3. II. C Energy Transformations

References and Resources