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30 Sound Waves
BROWARD COUNTY ELEMENTARY SCIENCE BENCHMARK PLAN
Grade 3—Quarter 3
Activity 30
SC.C.1.2.2
The student knows that waves travel at different speeds through different materials.
SC.H.1.2.3
The student knows that to work collaboratively, all team members should be free to reach,
explain, and justify their own individual conclusions.
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The student knows that to compare and contrast observations and results is an essential
skill in science.
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The student knows that a model of something is different from the real thing but can be
used to learn something about the real thing.
ACTIVITY ASSESSMENT OPPORTUNITIES
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The following suggestions are intended to help identify major concepts covered in the activity
that may need extra reinforcement. The goal is to provide opportunities to assess student
progress without creating the need for a separate, formal assessment session (or activity) for
each of the 40 hands-on activities at this grade level.
1. Play a tape or CD recording of a simple song that would be familiar to students. At various
points in the song, have them identify whether the music is loud or soft and high-pitched
or low-pitched. Have them describe how they would shake the rope to show the volume
and pitch of different sounds. (To represent volume, students would shake the rope in
higher or lower waves. To indicate pitch, they would shake the rope in longer or shorter
waves.)
2. Use the Activity Sheet(s) to assess student understanding of the major concepts in the
activity.
In addition to the above assessment suggestions, the questions in bold and tasks that
students perform throughout the activity provide opportunities to identify areas that may
require additional review before proceeding further with the activity.
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312
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activity 30 Sound Waves
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30 Sound Waves
OBJECTIVES
Students use a rope to demonstrate that
only the energy of a sound wave moves,
not the material through which it is moving.
They then use the rope to demonstrate
sound waves of different volumes and
different pitches.
For the teacher
1
1
1 pair
1
bowl, glass or metal, large*
bowl, glass or metal, small*
scissors*
spoon, large wooden*
*provided by the teacher
The students
operationally define pitch and volume
show that the material through which a
sound moves does not move, only the
energy of the sound itself moves
demonstrate differences in the
wavelengths of sounds of different pitches
and in the wave heights of sounds of
different volumes
PREPARATION
1
2
3
4
SCHEDULE
About 40 minutes
VOCABULARY
5
If possible, arrange to do the rope
portions of this activity outdoors.
Cut the ribbon into lengths of about 6
inches (15 cm), one piece for each team.
Make a copy of Activity Sheet 30 for each
student.
You will need a wooden spoon and two
bowls of different sizes for a class
demonstration. Test the bowls by hitting
them on the side with the spoon to make
sure you can produce sounds of
noticeably different pitches.
Each team will need a rope and a ribbon.
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pitch
volume
BACKGROUND INFORMATION
MATERIALS
For each student
1
Activity Sheet 30
For each team of two
1
1
rope
ribbon, 6-in.
The volume of a sound is its degree of
loudness. Its degree of loudness can be
controlled by varying the amount of force
used, or energy required, to make an object
vibrate and produce sound waves.
The volume of a sound depends on the
amplitude, or height, of its sound waves.
Sound waves of loud sounds have a greater
height than do sound waves of soft sounds.
The more energy supplied to an object to
produce a sound, the stronger the vibrations
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The pitch of a sound is its “highness” or
“lowness.” Sounds with a high pitch are sharp
and shrill, like a shriek. Sounds with a low
pitch are deep and resonating, like thunder.
Whereas volume depends on the strength, or
amplitude, of sound waves, pitch depends on
their frequency. Frequency is the number of
vibrations or waves per second. The faster an
object vibrates, the more sound waves it
produces per second. The more waves there
are per second, the higher the frequency and
the higher the pitch.
of that object and the greater the amplitude
of the resulting sound waves.
Activity Sheet 30
Sound Waves
Volume
1. Decide whether the volume of the sound produced by each wave is loud or
soft. Write loud or soft on the line.
a.
soft
b.
loud
Pitch
2. Decide whether the pitch of the sound produced by each wave is high or low.
Write high or low on the line.
(a)
a.
low
b.
high
(b)
Guiding the Activity
Give each team of two a rope and a length of
ribbon.
Have the members of each team pull the rope
fairly taut between them. Tell one student to
shake his or her hand up and down to move
the rope (see Figure 30–1). Ask, What do you
observe?
Students should see waves moving along the
rope from the shaken end to the other end
and back again.
Safety Note: Caution the students to
hold tightly to the rope so that it doesn’t
fly out and hit someone.
Ask, What is actually moving along the
rope?
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activity 30 Sound Waves
Accept all reasonable answers. Some
students may suggest that energy from
shaking the rope is transferred to the rope
and is moving along the rope.
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1
Additional Information
Guiding the Activity
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2
3
Additional Information
Figure 30-1. Students shake a rope to create waves.
Have students tie the ribbon to the middle of
the rope and then shake the rope again. Ask,
What happens to the ribbon?
It moves up and down but does not travel
with the waves.
Ask, What can you conclude about what is
moving from one end of the rope to the
other?
Students should suggest that the energy
from shaking their hands is transferred to the
rope and moving along the rope, but the rope
itself is moving only up and down.
Explain that the wave they have created is
like a sound wave, which carries sound
energy from one place to another. The sound
wave moves through the air or solid material,
but the air or solid material itself does not
move.
You may want to remind students that the
vibrations they observed in Activity 29
produced sound waves that moved outward
from the string.
Do the following demonstration: Hit the small
bowl gently with the wooden spoon to
produce a soft sound. Then hit the bowl hard
to produce a loud sound. Ask, What was
different about the two sounds you just
heard?
The first was soft and the second was loud.
Write the word volume on the board. Explain
that changing the volume of a sound makes
the sound louder or softer. Ask, How would
you define volume?
Students should suggest that the volume of a
sound is its loudness or softness.
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Guiding the Activity
Explain to students that the height of a sound
wave determines how loud or soft the sound
is—its volume. A higher wave produces a
louder sound, and a lower wave produces a
softer sound.
Invite students to try making higher and
lower waves with the rope.
After they have experimented, ask students,
How can you make higher and lower waves
when you shake the rope?
Tell students to use the rope to demonstrate
the wave heights of loud and soft sounds.
5
Students should say that they can produce
higher waves by shaking the rope up and
down a greater distance and can make lower
waves by shaking it a shorter distance.
Ask, How did you show a sound with a loud
volume? How did you show a sound with a
soft volume?
Students should say that they showed a loud
volume by shaking the rope up and down a
greater distance and a soft volume by
shaking the rope a shorter distance.
Use the spoon to hit the large bowl and then
the small bowl with about the same intensity.
Ask, How would you compare these two
sounds?
Students should say the sound produced by
the large bowl is low, and the sound
produced by the small bowl is high.
Write pitch on the board. Again hit the two
bowls in the same way. Explain to students
that they have just heard differences in the
pitch of a sound. Ask, How would you define
the word pitch?
6
Make sure that each team stands far enough
away from the next team so that there is no
danger of their ropes becoming entangled.
Students should suggest that pitch is how
high or how low a sound is.
Explain that the length of a sound wave
determines the pitch of the sound. The
shorter the wavelength, the higher the pitch
is. The longer the wavelength, the lower the
pitch is.
Invite students to try making shorter and
longer waves with the rope.
After they have experimented with the rope,
ask, How can you make longer and shorter
waves when you shake the rope?
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activity 30 Sound Waves
Students should suggest that they can shake
the rope faster to produce shorter waves and
slower to produce longer waves.
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4
Additional Information
Guiding the Activity
Additional Information
Have students use the rope to demonstrate
the wavelengths of sounds with a high pitch
and sounds with a low pitch.
Ask, How did you show a sound with a low
pitch? How did you show a sound with a
high pitch?
7
Students should say that they showed a
sound with a low pitch by shaking the rope
slowly and making long waves. They showed
a sound with a high pitch by shaking the rope
quickly and making short waves.
Give each student a copy of Activity Sheet
30. Explain that the activity sheet has
diagrams showing what different sound
waves would look like if we could see them.
The diagrams are similar to what the students
saw when they observed the rope.
Have students identify the first two wave
diagrams as loud or soft sounds. Have them
identify the second two wave diagrams as
high or low sounds.
REINFORCEMENT
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Have students gradually increase the height
of the waves to show gradually increasing
volume. Have them gradually increase the
length of the waves to show pitch gradually
getting higher.
SCIENCE JOURNALS
Have students place their completed activity
sheets in their science journals.
CLEANUP
Return the ropes and ribbons to the kit.
SCIENCE AT HOME
Have students and family members identify
the relative volume and pitch of various
sounds they hear at home. For each one,
have students describe or draw the shape
of the waves producing those sounds.
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Connections
Science Challenge
Science and Language Arts
Challenge students to combine volume and
pitch in the waves that they produce when
they shake the rope. Have them shake it in
such a way to produce waves like those of
loud high-pitched sounds, soft high-pitched
sounds, loud low-pitched sounds, and soft
low-pitched sounds. Students will need to
combine the speed and the height at which
they move their hands.
Ask students whether they know of any other
meanings of the word volume. (Students may
mention volume as a measurement and as
another word for a book.) Ask students to
consult a dictionary to verify their responses
or to learn these other meanings of the word.
Then ask them to write three sentences using
the three different meanings of the word.
318
Have students observe the waves in water.
Have them strike a tuning fork to set it
vibrating and then touch the tip of the fork
to water. Have them observe the resulting
waves. Then have students strike the
tuning fork harder and less hard to
produce sounds of different volumes and
water waves of different heights.
Sometimes the sound waves from one
vibrating object can cause another object
to vibrate at the same pitch. Students can
observe this by using two identical tuning
forks, as follows: Strike one fork to set it
vibrating and hold it close to (but not
touching) the other fork for a few seconds.
Then grasp the first fork’s tines to stop its
vibrations, and hold the second fork close
to your ear. The second fork will now be
vibrating and producing a sound of the
same pitch. Tell students that this
“sympathetic” vibration is called
resonance. Resonance occurs when the
sound waves produced by one object make
another object vibrate.
Have students make a stringed instrument
from a box with a hole in it. Have them
make strings of different lengths to
produce sounds of different pitches. Then
have them play sounds of different
volumes on their instrument.
activity 30 Sound Waves
Science and Music
Have students fill glasses to varying heights
with water. Challenge them to arrange them
in such a way as to create a harmonic scale.
Then have them try to create simple songs
with their scale.
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Science Extension