Exploring Sound: Length Makes a Difference

Kim Toops
Prairie Woods Elementary
New London, MN 56273
Based on an original activity from the Glencoe Physical Science Textbook,copyright 1999, p. 497
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Summary

In this elementary physics lab, students will begin to explore the relationship between the length of an object and the sound it produces as it vibrates, by using a wood or plastic ruler and the edge of a desk or table.

Learning Goals

This activity is designed for students to discover that the length of a sound-producing object affects the sound of the object. Students may be able to match the note made by the ruler with a note on the piano. Students will develop listening skills as they practice with the rulers. Vocabulary: vibration, pitch, sound

Context for Use

This is an introductory lab activity appropriate for any age students K-12. The actual activity was taken from a middle school-level physics textbook, and can be adapted for any age. Depending on how involved you'd like the students to get, the activity can last anywhere from 10 minutes to a few days if the students will be developing a piece of music with the sounds from the vibrating rulers. I plan to use this activity as an introduction to sound, but it could also be used as a final activity. It would be very appropriate for use in a music classroom as well.

Description and Teaching Materials

Materials needed: Wooden and plastic rulers, and a desk or table for each student or group of students. Each student will be given a wooden ruler or plastic ruler and asked to see if he or she can make different sounds with it. After a few minutes of exploration with the rulers, we will discuss as a class the different ways that sounds can be made with the ruler. If no one has discovered the method of placing the ruler flat on a desk with the free end extending beyond the desk, we'll all try that at this time. I'll have the students gently pull up on and release the free end of the ruler and talk about what they see and hear. We'll then move the ruler to allow more or less length to hang over the edge of the desk and repeat the experiment several times to hear different sounds. We'll also see if we can make the rulers play the notes to familiar songs. To further reinforce the idea that the shorter the ruler, the higher the sound and, the longer the ruler, the lower the sound, the teacher can play and show the students a child's xylophone or possibly the inside of a piano (with help from the music teacher.) The students will be able to see (and hear) this quite easily with either example. This activity is adapted from one in the Glencoe/McGraw-Hill Physical Science textbook, copyright 1999, page 497

Teaching Notes and Tips

The students need to be reminded to be careful with the wooden and plastic rulers, since they might break. Other than that, this is a very easy activity to implement. Our third grade textbook devotes a "whopping" three sentences to sound, so this is an activity I'll use to supplement that to help meet the third grade physical science standard.

Assessment

Students will achieve their learning goals if they can successfully move their ruler to make sounds and if they know that the shorter the object vibrating, the higher the sound and the longer the object, the lower the sound. The teacher will observe the students as they explore the sound a ruler can make and encourage them to match pitches.

Standards

3.II.C.1 Investigation of how sounds are made when objects vibrate

References and Resources

http://galaxy.net/~k12/sound/ The Science of Sound is a great website designed for use with primary students. It is a series of experiments about sound and its application to animals, music, and communications.