Science Extension: Pitch Vs. Length
Contributed by: Bose Corporation – In Harmony with Education Program
Grade Levels
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Elementary School
Junior/Middle School
Content Categories
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Band
Chorus
General Music
Orchestra
Technology
Description
―The Bose In Harmony With Education‖ program was created by a team of music, science, and math
educators led by MENC: The National Association for Music Education. Our goal was as simple as it was
ambitious. We sought to create an interdisciplinary music curriculum that would take students beyond
mere understanding. We wanted students to see, hear and feel the power and beauty of music as it
demonstrates the nature and science of the sounds that surround them in their daily lives.
Students in the Bose In Harmony With Education program learn through hands-on experience, by
creating and playing their own instruments.
The Bose In Harmony With Education program helps students achieve all nine of the curricular goals of
the National Standards for Music as well as the standards for math and science, adopted by national
consensus in1994. Interdisciplinary by nature, the Bose In Harmony With Education program particularly
emphasizes Standard 8, ―Understanding relationships between music, the other arts, and disciplines
outside the arts.‖
Exploring the connections between music, science and math also helps students reach many of the
standards adopted by professional educators in those related fields. And while the seven lessons, or
‖parts,‖ of the In Harmony With Education program curriculum are designed primarily for students in
grades five through eight, they have been and can be successfully adapted for use with both younger and
older students as well.
Standards
1. Understanding relationships between music, the other arts, and disciplines outside the arts.
Objectives
For this activity students will discover:
1. Sound is produced by vibrations.
2. The length of the vibrating source affects its pitch.
This lesson addresses National Science Education Standards:
A. All students should develop:
 Abilities necessary to do scientific inquiry.
 Understandings about scientific inquiry.
B. All students should develop an understanding of:
Properties and changes of properties in matter.
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Motions and forces.
Transfer of energy.
Materials
Pitch Vs. Length - Part 1
 Rulers (one per group; wooden rulers perform best; very stiff plastic rulers will work as well)
Pitch Vs. Length - Part 2
 2-inch PVC pipe (in various lengths, from 19" to 79 1/2", cut to the lengths shown in the attached
document). Three sizes per group. Note that:
a. The resonance of 2" and greater diameter pipes works best.
b. The 2" pipes are easier to store.
c. Lengths longer than 20" resonate well; short lengths are not very useful.
d. Since the width has no effect on the frequency, you may wish to add experimentation with the
same length, but different widths.
 Rounded end caps that fit the cut pipes. Three per group. Note that:
a. There is a cheap type of end cap available that is used for pipes that are not under pressure. You
may wish to try to find this option rather than the more expensive caps designed for pressurized
applications.
 Ping-Pong racket, rubber paddle, or rubber sandal (optional)
Pitch Vs. Length - Part 3
3/4" electrical conduit, cut to the lengths specified in the attached document (three lengths per group).
Note that standard conduit from a local hardware store should work. There may be some variance in pitch
due to different materials within the conduit.
 Rubber O-rings to fit around the electrical conduit (six per group)
 Hard mallets (optional)
Pitch Vs. Length - Part 4
 long board; nail; string (preferably thick fishing line), weight; pencils
Procedures
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Pitch Vs. Length - Part 1
Divide the class into groups. Have each group place a ruler on a desk or table so that about 8" of the ruler
extends beyond the edge of a table. The student performing the activity should hold the ruler to the table
firmly, with his or her hand about 1" from the edge. Bend the ruler slightly upward and quickly release it,
causing the ruler to vibrate.
Have the students listen to the sound produced.
Then, ask them to shorten the distance the ruler extends over the table by 1". Again, they should hold the
ruler firmly and make it vibrate.
Ask the students to repeat this several times, altering the length that the ruler extends over the table and
noting the changes in sound.
Ask the students to answer the following questions (either in their groups or individually):
a. What do you think causes the sounds? What evidence do you have to believe this?
b. How do the sounds change as you move more of the ruler onto the table?
c. Do the vibrations appear faster or slower as you move more of the ruler onto the table?
d. If you wanted to build a ―ruler-a-phone,‖ an instrument that make sounds with rulers, how many rulers
would you need to produce eight musical notes?
Pitch Vs. Length - Part 2
Divide the class into groups. Have a student in each group take three lengths of PVC pipe and hold them
in the air with one hand. Then, have them strike one of the open ends with an open hand or paddle.
Ask the students to listen to the sounds produced by all three lengths.
Ask the students to answer the following questions (either in their groups or individually):
a. When you line up the pipes from lowest to highest pitch, what do you notice about the lengths of the
pipes? Draw a picture to help demonstrate what you observed.
b. Can you vary the pitch by changing the force used to strike the pipe? Is there any change in the sound
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produced if the pipe is struck harder or softer?
c. Find something else in the room to strike one end of the tube. Did the pitch change?
d. If you wanted an instrument made from open tubes and you wanted it to play 10 different notes, how
many pipes would you need? Why do you think this answer is correct?
Have each group place a rounded end-cap on one of the tubes. Then, have them:
a. Strike the tube with an open hand.
b. Tap the open end lightly on the floor.
Ask the students to answer the following question (either in their groups or individually):
a. What happened to the pitch of the sound? How would you explain this change?
Have the students in each group cap their remaining two tubes on one of the open ends and line up the
pipes from lowest to highest pitch.
Ask the students to answer the following questions (either in their groups or individually):
a. What do you notice about the lengths of the pipes? Draw a picture to help demonstrate what you
observed.
b. Did the order of the pipes change from the way you lined them up when both ends were open?
(optional) Have students use different length pipes to create a piece of music.
Pitch Vs. Length - Part 3
You may wish to bring in a very long piece of conduit and suspend it from the middle. Strike it to
demonstrate to the class the low frequency produced.
Divide the class into groups, giving each group three lengths of conduit and six O-rings. Have the
students place the rubber O-rings 1/4 of the distance in from each end of the electrical conduit. (An easy
way to do this is to take a piece of paper equal to the length of the conduit and fold it in half twice. Then
measure off the distance of the folded paper from the ends of the conduit. You may wish to mark this
distance for other classes to save time.)
Laying the conduit on a hard surface, have the students strike it with a mallet or pen or pencil. Ask them
to repeat this on the other two lengths, making note of any changes in sound.
Have the students move the rubber O-rings to several different positions other than where they were
originally marked, being sure to keep the conduit from resting directly on the table. Ask them to observe
and record what happens.
Ask the students to answer the following questions (either in their groups or individually):
a. When you line up the conduit from lowest to highest pitch, what do you notice about the lengths of the
conduit? Draw a picture to help demonstrate what you observed.
b. Did the pitch change if you struck the conduit harder or softer? Is there any change in the sound
provided if the conduit is struck harder or softer?
c. If you wanted a very low pitched sound, what length pipe would you use?
d. Why do you think each length of conduit can only produce one type of sound?
e. If you wanted an instrument with 50 different pitches (like a xylophone), how many different lengths of
pipe would you need?
f. As you move the O-rings from their original positions, what happens to the sound?
g. Why do you think the sound changed as the O-rings were moved?
Pitch Vs. Length - Part 4
Get a long board with a nail near one end.
a. Place several books near the nail to keep the board from tipping over (see diagram in attached
document).
b. Tie a string on the nail; tie a weight on the other end of the string.
c. Set two pencils on top of the board and under the string as shown in the diagram below.
d. Place a round pencil at the end of the string to keep the string from binding on the board.
Now, ask the class to observe while you strum the string between the pencils. Ask them to answer, either
in class discussion or in writing:
a. When the string is strummed, why is a sound produced?
b. When the pencils are moved closer together, does the pitch of the sound change?
c. If you wanted to produce a high-pitched sound, how would you arrange the pencils? Draw a picture to
help explain your thoughts.
d. Are you limited to a few different pitches or can you make many different pitches?
e. Why do you think musicians playing many string instruments press down on the strings with their
fingers while playing?
f. List two string instruments that musicians press down on the strings to play.
3. Without touching the pencils, pull on the string by the weight as you continue to strum the string. Caution:
Do not pull too hard or the weight will fall, possibly causing an injury. Ask the students to answer:
a. How is the pitch affected as you pull on the string?
b. There are adjusters at the top of a guitar to change the tension (pull) on the strings. How do you think
this is used in tuning the instrument?
Pitch Vs. Length - Summary
1. Based on the four different activities they used to study sound, ask students what general rule they can
make about the length of the object and the pitch it will produce.
Note: In the summary questions to these activities, we expect students to see the relationship between
size and frequency (pitch). It may be important to note there are a few exceptions. For example, the mass
of two strings of equal length also will affect their frequency. Those with more mass move slower and
have a lower frequency (pitch). If you discuss Newton‘s laws of motion in your curriculum, this is a good
example.
Attachments
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722_PitchVs.Length