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Kathleen Moore O. W. Holmes
955 W. Garfield Blvd.
Chicago IL 60621
This lesson is designed for grade levels 1 - 3.
1. To understand that sound is caused by vibration.
2. To understand that sound travels through solids, liquids and gases.
3. To understand that high pitched sounds are caused by more vibrations and low
pitched sounds are caused by fewer vibrations.
plastic ruler(s), tuning forks of 2 or 3 different pitches, ping-pong ball
attached to a string with tape, boom-box-type radio, balloon filled with air,
paper plate, tiny pieces of torn paper, baggie filled with water, scissors,
several glass bottles of the same size, large container for water, styrofoam
cups, wire coat hangers, string (different types), wire cutters, pencils (with
wooden ball attached to the eraser end if possible), stopwatch, flower pots of
varying sizes attached to rope, long tubes of PVC pipe cut to different lengths
for different tones, xylophone, plastic straws, tape.
1. Ask children if anyone knows what a vibration is. Ask children to vibrate
their bodies. Write vibrate on board. Put a plastic ruler overhanging the edge
of a table; hit the ruler and watch it vibrate. Ask: "Can we see the vibration?
Can we hear the vibration? Can we feel it?" Show tuning fork; hit; listen;
touch vibrating tuning fork to ping pong ball attached to a string. Observe the
effect; ask same questions. Pass tuning forks around so children can experience
the sound and feel the vibration; note differences in pitch. Hold inflated
balloon in front of boom-box speaker with volume turned up loud. "Can you feel
the vibration? Where is it coming from?" Place small paper plate with tiny
pieces of paper on it on top of speaker. (Boombox must be turned so that
speakers are facing up.) Observe what happens to the papers. Explain that all
sounds are caused by something vibrating; sound is vibration, etc.
2. How do vibrations from tuning fork and ruler reach us as sound? The
vibrations cause waves to carry sound through the air. (You will perhaps need
to discuss waves, depending on age and experience of children.) "We know sound
travels through air. Does it travel through a solid? Put your ear on the desk.
Tap the desk. What do you hear?" Try several such examples. "Does sound
travel through a liquid?" Get children to talk about experiences they have had
such as talking underwater in the bathtub or swimming pool. Can they hear sound
under water? "Try putting a plastic baggie filled with water next to your ear.
Have another child speak loudly directly into the other side of the baggie. Can
we hear the sound through the water? Does sound travel through a solid, a
liquid, and a gas (air)? When was it the loudest?" (through the solid) "Why
do you think this may be true?" (The molecules in a solid are more tightly
packed, so the vibration can travel without being dispersed as it does in air.)
3. Show a child's xylophone or an autoharp. Strike a short bar, then a long bar
and ask children what they heard. Do the same for the lengths of PVC pipe.
(Hit the end of the pipes with the palm of your hand.) Make a kazoo out of a
plastic straw by flattening one end and cutting it into a triangular shape;
blow. As one person blows through the kazoo, another takes a scissors and snips
an inch or so off the end. Keep doing this and ask the students to notice
what's happening to the sound as the straw gets shorter. Help them relate the
shortness of length to high pitch through a variety of such experiences.
4. Now allow the children to experiment and "play" with all the materials so
that they develop strong physical understanding of vibrations in all the ways
that have been presented. Have a set of 8 identical bottles and a container of
water and have them fill the bottles with varying amounts of water. See if they
can match the scale of the bottles to that of the xylophone. Give children the
opportunity to make a string phone or wire-hanger chime. (Tie a length of
string to each end of a wire coat hanger. Put the other end of each string in
your ears, tap the hanger against something like a desk. Listen for the ringing
through the string.)
1. Children must: Arrange bottles with varying amounts of water in row
according to pitch. Explain the relationship between the amount of water and
the pitch. Tell what is vibrating. Blow across or just into the top of each
bottle and explain how the relationship between pitch and the amount of water in
the bottle changes. Hypothesize as to why this might be.
2. Make a stereo coat hanger as explained above. Tell how you might make one
with a higher pitch (shorter wire). Cut hanger with wire cutter to get
different lengths and different pitches.
3. Make a straw kazoo. Listen to its pitch. Have your partner cut off an inch
or two with a scissors while you are blowing. What happens to the sound? Cut
off another inch. What do you notice now?
4. Listen to the sound of each tuning fork. (Strike tuning fork on your shoe
then put it to your ear.) Arrange the tuning forks from highest pitch to
lowest. What do you notice about the forks when they look this way?
The shorter the tube (or straw, or xylophone key or amount of water in the
bottle) the higher the pitch. The longer the tube, the lower the pitch. Pitch,
(high and low) is caused by the frequency, or number, of vibrations per time.
More vibrations per time ("bigger" frequency) = higher pitch; fewer vibrations
per time ("smaller" frequency) = lower pitch.
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