Developers:

Elizabeth Lawrence
Downingtown Area School District
Lionville Elementary
Downingtown, PA

Walt Platek
Senior Scientist/Analytical Research
Rohm and Haas Company

Grade Level:

4 through 6

Time Period:

3 periods of 45 minutes

Discipline:

Physical Science

Goals:

Upon completion of this unit, the student will:

1. conclude that sound travels by means of vibrations of matter.
2. evaluate and attempt to explain the sound inquiry using prior knowledge of states of matter.
3. understand how sound waves travel.
4. test the relationship between frequency of vibration and perceived pitch.

Objectives:

Upon completion of this unit, the student will be able to:

1. explore sound wave vibrations in objects.
2. test and analyze how sound travels differently through vibrations passing through three different states of matter.
3. test and prove the theory that the size of an object vibrating affects the frequency of the sound waves, and therefore changes the pitch of the sound.
4. test the theory that the stiffness of an object affects the frequency of the sound waves and, therefore, the pitch of the sound.
5. test and analyze how varying the volume of water in a vessel changes the frequency and therefore the pitch due to the length of the vibrating matter.
6. define the terms frequency and pitch.

Background:

Scientific method is based on logical steps that lead to a conclusion based on testing. Sound waves must travel through matter. Without the vibration of some state of matter there is no sound. There is no sound in a vacuum because there is no material to vibrate. Light waves are produced by vibrations of electrons and are in this way similar to sound waves. The difference is that, once produced, light waves need no matter to be propagated through space and will travel through a vacuum. The three states of matter that are to be tested are solid, liquid, and gas. These states of matter have a different atomic make-up.

The small particles that make up a gas are widely separated and roam about the container freely. The particles of liquids are close together but still free to move around each other. A solid has tightly packed atomic particles. Sound needs vibration and the more particles packed together the greater the vibration. By changing the size, tightness, or the mass of the vibrating object you change the frequency of the sound. Frequency is the number of vibrations per unit of time. By changing the sound wave's frequency you are able to change the pitch of the sound. Columns of various lengths produce different frequencies when air is vibrating inside them. This occurs because the length of the air column determines the length and the sound wave that is supported. Since wavelength and frequency are inversely proportional, the frequency and pitch increase as the column length decreases.

Activity 1: Sound Discovery
Time period: 45 min.

Materials:
Box with lid, ball, scissors, crayons, pennies, paper cups, string, wire hangers, pencils, slinky, tuning fork, bowl of water, any musical instruments available. (This exploration does not depend on any one material and can be performed with just a few of the listed materials or more materials than are listed.)

Objective:
Students will explore the sounds that objects make and try to explain what makes the sound by manipulating the object.

Procedure:
Teacher will begin class by setting a box with a ball inside it on the front table and asking students to guess what is inside. The box will have a lid so students will probably ask you to shake the box so they are able to guess what is inside by the sound it makes. Have students guess with other objects as well. Scissors or crayons work well. Ask students how they knew what the objects were. How did they get the object to make sound? You shook it! Take students' ideas about how sound travels and what sound is and record on the board.

Exploration Stations:
Students will work in small groups and rotate around the various stations, exploring different things that create sound.

1. Using a tuning fork tapped against the heel of a shoe or a rubber mallet then placed into water, students can see the vibrations. (NOTE: Striking the tuning fork with a hard object might damage it and change its frequency.)
2. Paper cups and string used to create a telephone teach students about how vibration is sent through the string when you suggest that one student pinch the line and then let go.
3. Wire hangers and two strings tied to each side. Students put one string around each pointer finger so that hanger is hanging down in front of them. Place the fingers into students ears. Do Not Place String in Ears. Have another student tap hanger with pencil. What happens when the tapping student touches the string? Listen to the tapping without the string near your ears.
4. Use any type of musical instrument available. Split the types of instruments up to create separate learning stations. Wind, string, and drums should all be placed in separate places. Circulate room. Ask students to explain what creates the sound. Have students fill out worksheet #1 (PDF file, see below) to guide their exploration. After the students have had time to explore with sound, return to the board to see if students want to add anything about sound. Students are now ready to learn that sound is caused by vibrations. Discuss some of the objects that they explored; what was vibrating?

Sound Worksheet #1: Exploration  (PDF, 16K)

Activity 2: Sound in the three forms of matter
Time period: 45 minutes

Materials:
sandwich size Zip-lock bags, clean sand, water, lab sheet (copy included)

Objective:
Students will test and analyze how sound waves or vibrations travel differently through a solid, liquid, and a gas. Students will conclude which form of matter is the best carrier of sound waves and why.

Procedure:
Prepare three bags for each group of 4 students. First bag will contain 1 1/2 cups of clean play sand. Remove all air before sealing bag. Label this bag # 1 with a marker. Bag labeled #2 will contain 1 1/2 cups of water with all of the air removed. Bag marked #3 will be full of air. Students work in their groups and will use a pencil to tap table as an ear is placed on each bag in turn. The vibrations from the tapping will travel through the 3 different states of matter. Students will come to a consensus about which state of matter is the best for carrying sound. Students may record their observations on worksheet #2. Students should come to the conclusion that sound travels through these three states of matter differently. A solid is the best transmitter of sound, then water, and lastly, air. Students will discuss results among their groups and, using what they have discovered, create ways to alter the amount of sound a guitar, a student in a classroom, and a noisy group of kids make. See worksheet #2 continued. When the whole class gets together have students share their ideas and creations.

Sound Worksheet #2: Sound through Matter  (PDF, 16K)

1. Which state of matter carried sound the best?
2. Which state of matter didn't carry sound well?
3. Were your predictions correct?
4. Why do you think you got the results you did? (Atomic particle make-up)
5. How does most sound that we hear travel?
6. What other experiments can we try?
7. Why would Native Americans listen to the ground?

1. Compare cups and long string telephone versus whisper down the lane at the same distance apart.
2. At home: Talk under water in tub and compare with in the air.
3. Students can create inventions for keeping sound contained or making sound louder.

Activity 3: Changing the Sound Waves Frequency
Time period: 10 to 15 min. for each of four centers

Materials: For all 4 centers
Learning Center 1. Metal spoons of various sizes with two strings tied on each spoon
Learning Center 2. Wooden boards with 6 nails pounded in as shown below, 3 similar rubber bands
Learning Center 3. 4 glass baby food jars with water in various levels from least to greatest, pencil
Learning Center 4. Wooden boards, 3 nails pounded as shown below, 3 key hole screws, fishing line
Learning Center 5. 8-12 plastic bottles (20 oz. spring water or soda bottles work well), water in varying levels of least to greatest. (create 2 centers from these materials.)

Procedure:
Students will be divided into 6 groups, two stations will be set up for Learning Center 5 to insure small groups of no more than 5 students per group. Learning Centers will be set up prior to class. You may wish to have 2 stations for some of the other center activities to allow for more hands on activity, and smaller groups. Worksheets are included, but fifth grade students should develop their own recording method for gathering and presenting data. Stress the need for quiet, since these are listening exercises.

Learning Center 1

Objective:
Students will test and analyze the theory that length changes the frequency of the sound waves, and therefore changes the pitch of the sound.

Procedure:
Large and small metal spoons with two strings tied to each spoon will be tested by students, one at a time. The two strings will be wrapped around the student's pointer fingers, then the fingers go into the student's ears. Do not put string in your ear! The spoon is then hanging between the two strings and another student will tap the spoon. Students will repeat the steps with all the sizes of spoons. Students will compare the pitch of the various sizes of spoons and come to a consensus. Is the pitch of the smaller spoon higher or lower than the larger spoon? Students can fill out worksheet #4.

Sound Worksheet #3: Learning Centers  (PDF, 11K)

Learning Center 2

Objective:
Students will be able to test and analyze how length of a vibrating object affects the frequency of the sound waves, and therefore changes the pitch.

Procedure:
Teacher prep ahead: Pound nails into board as shown. There should be three sets of nails of ascending length on the board. Using 3 identical rubber bands, cut once to open. Tie one end to underneath of each nail head. Stretch each so that the thickness of the rubber band is the same for all 3 lengths. You may need to experiment with the tightness. Students will pluck each band, listening to the pitch of each. Students should come to a consensus about size and pitch. This should be linked to a similar statement regarding frequency. Students can record data on the #4 worksheet provided.

Learning Center 3

Objectives:
Students will test and analyze how various levels of water affect the pitch and therefore the frequency of sound waves.

Procedure:
Teacher prep ahead: Fill jars with various amounts of water. Students will tap glasses below water line to determine how volume/mass affects pitch. Students will come up with a statement regarding volume of water and frequency. Students can use worksheet provided to record findings. Circulate the room to assure student understanding. What is vibrating?

Learning Center 4

Objectives:
Students will test and analyze how tightness changes frequency and pitch of sound produced when fishing line is plucked. (a string instrument can also be used)

Procedure:
Teacher Prep: A board with 3 large headed nails pounded into it as shown to the right; and 3 key holed screws, screwed into the other end so that fishing line can be tied to the nails and wrapped around the key hole screws. Teachers may want to set each line at varying tightness and tie off to quicken the process. The screws should be able to be turned to tighten and loosen. Students will test the fishing line in 3 varying tightnesses, by plucking each string. Students should come to a conclusion about how tightness affects pitch. Students may record a statement on the worksheet provided in this document. Question students as to how they think tightness affects the sound waves.

Learning Center 5

Objective:
Students will use columns of air in differing lengths to determine how length of a vibrating object effects pitch.

Procedure:
Teacher Prep: Take up to 6 plastic bottles and fill with water in ascending amounts. This will provide students with many different pitches to compare. Students will need to practice blowing over the top of the bottles to create a clear tone. Students who have wind instrument experience will be a big help in demonstrating the proper technique. Students need to be mindful of what is creating the sound. Vibrating columns of air at different lengths produce different frequencies.

This experiment is courtesy of