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Content Benchmark P.8.C.2
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 Physical Science Matter Force and Motion Energy P.8.C.1 P.8.C.2 P.8.C.3 P.8.C.4 P.8.C.5 P.8.C.6 Content Areas Nature of Science (NOS) Life Science Earth Science Physical Science  Students know vibrations (e.g., sounds, earthquakes) move at different speeds in different materials, have different wavelengths, and set up wave-like disturbances that spread away from the source uniformly.   E/S

If a tree falls in the forest and no one is around to hear it does it make a sound?  This is a philosophy question that might be answered scientifically.  A wave is a transmission of energy by a series of vibrations.  Many types of waves are disturbances that travel through a medium and transport energy from one location to another without transporting matter.  The material or substance through which the wave energy is transported is called the medium. In turn, the medium can be a solid, liquid, or gas, which is a collection of interacting particles.

Sound is a wave produced by vibrating objects and needs a medium through which to travel.  To help answer the question about the tree in the forest, one must think of sound as a longitudinal wave. But first, the difference between transverse and longitudinal waves needs to examined.  Characteristics of waves, such as, wavelength, frequency, amplitude, and speed (velocity) will also be explored.  Then how waves transfer energy differently in different materials will be investigated. Next one has to understand the relationship between velocity, wavelength, and frequency.  The causes and effects of the Doppler effect will be looked at as well.

Types of Waves

A mechanical wave may be longitudinal, transverse, or a combination of both. We classify the wave type based on the path in which the medium vibrates in relation to the movement of the wave’s energy.  Mechanical waves need a medium in order to transfer their energy from one place to another. This transmission of energy cannot happen in a vacuum (i.e., a place where no medium exists) for mechanical waves.  In a transverse wave the particles of the medium vibrate in paths that are perpendicular to the direction of motion of the wave.  The illustration shows the disturbance is perpendicular to the direction of travel of the wave. Figure 1.  Transverse Wave
(From http://www.phys.ualberta.ca/~trpk/phys100/waves/waves.html)

Remember that transverse waves are always distinguished by particle motion being perpendicular to wave motion.

For an animation of a transverse wave, go to http://www.acoustics.salford.ac.uk/feschools/waves/wavetypes.htm - introd.

For additional information related to waves, visit http://www.glenbrook.k12.il.us/gbssci/Phys/Class/waves/wavestoc.html.

Another type of mechanical wave is a longitudinal (or compression) wave in which a disturbance causes the particles of the material to vibrate in a direction parallel to the direction of motion of the wave.  The disturbance is often referred to as a pulse when the wave motion is a single disturbance or of short duration.  The illustration below shows, that for longitudinal waves, the medium vibration is in the same direction as the motion of the wave. Figure 2.  Longitudinal Wave
(From http://www.phys.ualberta.ca/~trpk/phys100/waves/wave2.jpg)

Keep in mind that for longitudinal waves the disturbance is parallel to the direction of travel of the waveSound waves are longitudinal waves.  Sound waves happen when the atmosphere is alternately compressed and stretched. The backward and forward motion of a speaker or the clapping of your hands produces these sound waves. The P waves of an earthquake are also an example of a longitudinal wave.

For an animation of a longitudinal wave, go to http://www.acoustics.salford.ac.uk/feschools/waves/wavetypes2.htm.

The third type of mechanical wave is often referred to as a surface wave, which combines properties of both transverse and longitudinal waves.  Surface waves occur on Earth’s surface when generated from an earthquake and surface waves are also seen traveling along the surface of an ocean.  With a surface wave, the particles of the medium travel in a circular motion compared to the direction of energy transfer.  Only the particles at the surface of the medium experience the circular motion, which is shown in the illustration below. Figure 3.  Surface Wave
(From http://www.glenbrook.k12.il.us/gbssci/Phys/Class/waves/u10l1c.html)

For a wave to be generated, there is a preliminary displacement of a molecule someplace in the medium.  Just as an earthquake has a focus, any wave traveling through a medium has a source. The molecules, which are displaced from their equilibrium position always progress in the same direction as the starting place of the vibration.

Properties of Waves
To better understand waves, we will now look at their properties, or in essence, dissect a wave.  First we will look at a transverse wave, and then, make a comparison to the longitudinal wave.  The image will show the parts of the wave. Figure 4.  Crest and Trough

In the figure of the transverse wave above, the line running through the center of the wave corresponds to the rest position or equilibrium position of neutral molecule movement.  The crest is the point where the vibration has the most amount of positive displacement from the rest position.  Conversely, the trough is the point where the vibration has the greatest amount of negative displacement.  The maximum displacement of any molecule in the medium relative to equilibrium is called the amplitude of the wave.  When thinking about sound waves, the “volume” of the sound is strongly linked to the sound waves’ amplitude.

Now to compare the transverse wave to the longitudinal waves look at the diagram below. Figure 5.  Compression and rarefaction in a longitudinal wave.

A longitudinal wave has compressions and rarefactions, which are analogous to the crests and troughs of the transverse wave.  A compression is the part of the longitudinal wave where the molecules of the medium are pushed closer together (e.g., higher pressure, more dense).  A rarefaction is the part of a longitudinal wave where the molecules of the medium are spread apart the most (e.g., lower pressure, less dense).

If we look at a single molecule in the medium, the time it takes for its motion to repeat itself is called the period (T) of a wave and it is measured in seconds.  The number of times the motion repeats itself in a specific time interval is known as the frequency (f) of the wave.  When referring to sound, frequency is equivalent to pitch.  In other words the frequency is the number of cycles per second (cycles/second).  Frequency is measured in Hertz (Hz), which is equivalent to cycles per second.  Frequency and period are inversely proportional to each other, as represented by the equation The wavelength ( ) is the distance the wave energy travels in the time it takes to complete one cycle.  A wavelength can be measured from crest to crest (compression to compression) or trough to trough (rarefaction to rarefaction). Figure 6.  Representation of wavelength.

For a wave, the speed is the distance traveled by a given point on the wave (such as a crest) in a given interval of time. Represented in equation form, .  Wave speed depends upon the properties of the medium through which the wave is moving. A change in the properties of the medium will cause a change in the speed, or if the wave transfers from one medium to another. The speed of a wave is also a ratio of wavelength to period, which in equation form is . This equation is known as the wave equation. It states the mathematical relationship between the speed (v) of a wave and its wavelength ( ) and frequency (f). Using the symbols v, , and f, the equation can be rewritten as .  The important thing to remember is that wave speed is dependent upon medium properties and independent of wave properties.

Further detail about waves can be found in the HS TIPS Benchmark P.12.C.1

Behavior of Waves
When waves travel through a medium they can reach the end of that medium and come across another medium or obstacle.  There are several possible results of a wave encountering a barrier, a boundary, or another medium.  One outcome is that a wave may be diverted (reflected) in the opposite direction.  For example, a sound wave may come into contact with a wall and bounce back so that you hear an echo, which is a type of reflection.  Direction change will occur with a reflected pulse, and also, the amplitude will be less than the amplitude of the incident pulse because energy is not completely conserved within the pulse (i.e., some energy is transferred to the reflecting barrier).

http://hyperphysics.phy-astr.gsu.edu/hbase/Sound/reflec.html.

As a wave encounters the barrier between two media, some of the energy will be reflected and some will be transmitted from the old media into the new media. If the differences between the media properties are small, most of the wave’s energy will be transmitted and very little will be reflected.  If the two media have very different properties then little energy will be transmitted and most will be reflected.  Finally, if the wave travels from a less dense to a denser medium the reflected wave will be inverted.

Waves can also change direction when traveling from one medium through another and this is called refraction.  The speed and wavelength of a wave changes as it passes into a different medium causing the path of the wave to bend or refract.  With sound waves the more elastic the medium the faster the wave travels.  As a result sound waves travel faster through solids than they do liquids, and faster in liquids than in gases.  The speed of sound in air depends on the properties of air specifically the temperature and the pressure. A sound wave will travel faster in a less dense material than a more dense material within a single phase of matter.  Therefore sound travels faster in warm air than in cool air. The two figures below demonstrate why sounds can be heard at farther distances at nighttime, a phenomenon entirely due to refraction. Figure 7.  In the daytime the air near the Earth’s surface is warmer than the air above
and sound waves are refracted upward.
(From http://www.hk-phy.org/iq/sound_night/sound_night_e.html) Figure 8.  At nighttime, the air near the Earth’s surface is cooler than the air immediately above and sound waves are refracted downward.
(From http://www.hk-phy.org/iq/sound_night/sound_night_e.html)

Diffraction denotes a change in the direction of a wave when passing through an opening or around a barrier in its path.  Water and sound waves can diffract around corners or openings.  With increasing wavelength the amount of diffraction increases and the opposite applies to decreasing wavelengths Figure 9.  This photo shows water wave diffraction near the northern
coast of Norway. Waves bend as the pass around islands and coast
promontories creating complex interference patterns.

http://www.glenbrook.k12.il.us/gbssci/phys/Class/sound/u11l3d.html.

Doppler Effect
Everyone is familiar with the sound of a siren on a moving vehicle.  As the vehicle draws near, the apparent pitch of the siren is increased; as the vehicle passes and then moves away, the apparent pitch is decreased.  The Doppler effect is perceived when the starting place of the waves is moving with respect to an observer.  The Doppler effect is the apparent shift in pitch (frequency) of a source of sound because of the relative motion between the source and the observer.  Water waves, sound waves, light waves, etc. can all exhibit the Doppler effect.  We are most familiar with sound and the picture below demonstrates the Doppler effect in a sound wave. Figure 6.  Doppler Effect
(From http://www.glenbrook.k12.il.us/gbssci/Phys/Class/waves/u10l3d.html)

For an applet of the Doppler effect, go to
http://www.lon-capa.org/~mmp/applist/doppler/d.htm

http://hyperphysics.phy-astr.gsu.edu/Hbase/Sound/dopp.html

Another resource for information on the Doppler effect and sonic booms can be found at http://www.kettering.edu/~drussell/Demos/doppler/doppler.html

Content Benchmark P.8.C.2

Students know vibrations (e.g., sounds, earthquakes) move at different speeds in different materials, have different wavelengths, and set up wave-like disturbances that spread away from the source uniformly.   E/S

Common misconceptions associated with this benchmark

1. Students have difficulty understanding the correct characteristics of sound waves.

Consider the following statements showing student confusion about sound waves
(from: http://www.eskimo.com/~billb/miscon/opphys.html).

• Loudness and pitch of sounds are confused with each other.
• You can see and hear a distant event at the same moment.
• The more mass in a pendulum bob, the faster it swings.
• Hitting an object harder changes its pitch.
• In a telephone, actual sounds are carried through the wire rather than electrical pulses.
• Human voice sounds are produced by a large number of vocal chords.
• Sound moves faster in air than in solids (air is "thinner" and forms less of a barrier).
• Sound moves between particles of matter (in empty space) rather than matter.
• In wind instruments, the instrument itself vibrates not the internal air column.
• As waves move, matter moves along with them.
• The driver changes the pitch of whistles or sirens on moving vehicles as the vehicle    passes.
• The pitch of a tuning fork will change as it "slows down", (i.e. "runs" out of energy)

As suggested by Mary O’Leary, in the referenced article, a conceptual change model may be the best way to address these misconceptions.  Students confront their preconceptions, and through the conceptual change processes, develop a scientifically accurate model of the concept.  Background information is given on sound and then several lesson plans are provided for use with students.  Students confront the preconceptions through the activities and from there develop a more accurate idea of the concept.  The lessons provided are geared to 4th grade students but they can easily be adapted to older students.  The lessons and activities are described in great detail and are easy to follow.

For further information on this misconception and for strategies to address it, visit http://www.eskimo.com/~billb/miscon/opphys.html

2. Students incorrectly believe that an object must vibrate only at its natural resonant frequency.

Students believe that waves traveling through different media will change a sound’s frequency.
In her Master’s thesis, Katherine VerPlanck Menchen discusses these misconceptions and curriculum she developed to help students address the effects on the frequency of a sound with respect to resonance and propagation.  The curriculum uses guided inquiry labs to explore sound in a hands-on style.  The results are analyzed and evaluated in the article.

To read this thesis, go to
http://perlnet.umephy.maine.edu/research/MenchenMSTthesis.pdf.

3. In regard to the Doppler effect, students incorrectly believe that the pitch is constantly changing as the object gets closer.

Perhaps this misconception springs from the common example that teachers use to discuss the Doppler effect: a siren on a passing police car. In this case, the police car passes by an individual, and in fact, does get closer to the person hearing the siren. But getting closer does not mean the pitch of the siren changes. Actually, the volume gets louder as the police car gets closer. The pitch does change when the relative direction of the police car with respect to the hearing person does change. At the instant the siren is no longer approaching the individual, but now is going away, is the instant the pitch changes.

The Physics Forum website has several discussions from teachers and their students. One discussion describes how many times students still retain misconceptions despite instruction.  One teacher describes that some misconceptions are ingrained and are extremely difficult to dispel.  The forum also discusses misconceptions introduced by textbooks and analogies used in the classroom.

To access the Physics Forum, go to

For an interesting article, go to http://www.physicsforums.com/showthread.php?t=200359

Content Benchmark P.8.C.2

Students know vibrations (e.g. sounds, earthquakes) move at different speeds in different materials, have different wavelengths, and set up wave-like disturbances that spread away from the source uniformly.  E/S

1st Item Specification: Understand that sound is produced and carried by molecules.

Depth of Knowledge Level 1

1. Sound is produced when
1. molecules push against each other causing vibrations.
2. molecules release photons of energy.
3. the electrons release light energy.
4. energy is traveling at the speed of light.
1. The human voice is the result of
1. lungs pulling air in through the nose.
2. vibrations in the vocal chords.
3. the placement of the teeth.
4. moist air exiting the lungs.
1. What types of waves are sound waves?
1. Electromagnetic
2. Longitudinal
3. Transverse
1. The unit that measures the intensity of sound is called
1. decibel.
2. Hertz.
3. meter.
4. lumen.

Depth of Knowledge Level 2

1. A sound wave is a longitudinal, mechanical wave; not a transverse electromagnetic wave. This means that
1. particles of the medium move perpendicular to the direction of energy transport.
2. a sound wave transports its energy through a vacuum.
3. particles of the medium regularly and repeatedly oscillate about their rest position.
4. a medium is required in order for sound waves to transport energy.
1. The diagram below shows sound waves traveling away from a vibrating bell. Use the diagram below to answer the following question. Which of the following factors would impact the speed of the waves?

1. The direction of the wave as it vibrates away from the bell.
2. How hard the bell was struck to initiate the vibrations.
3. Temperature and medium through which the sound is traveling.
4. Whether the bell was made of steel or some other type of metal

2nd Specification: Recognize that waves transfer energy differently in different materials.

Depth of Knowledge Level 1

1. How does the air temperature affect the speed of sound waves traveling through the air?
1. As the temperature decreases, the speed increases.
2. As the temperature increases, the speed decreases.
3. As the temperature decreases, the speed decreases.
4. As the temperature increases or decreases, the speed does not change.
1. Sound waves more the fastest through which of the following media?
1. Water
2. Steel
3. Oxygen
4. Oil
1. The speed of sound in air is most affected by
1. gusting winds.
2. volume of air moving.
3. temperature changes.
4. cloud cover.

Depth of Knowledge Level 2

1. A student observes a bell placed in a vacuum jar. After the vacuum jar is evacuated the bell is rung but no sound is heard. The student states that this is because
1. all sound vibrations are reflected in the glass jar.
2. sound vibrations cancel each other.
3. sound vibrations must travel through a medium.
4. the bell ringer does not work in a vacuum.
1. How does the speed of sound in water compare to its speed in air?
1. The speed is slower because the molecules in water are closer to each other.
2. The speed is the same because it is constant in all media.
3. The speed cannot be compared without knowing the temperature.
4. The speed is faster because the molecules in water are closer to each other.
1. Use the figure below to answer the following question. (From http://www.nasa.gov/)

What happens when sound waves strike the ear drum?

1. Sound waves are absorbed by the eardrum.
2. Sound waves cause the eardrum to vibrate.
3. The walls of the outer ear change shape.
4. The bones of the cranium vibrate.

3rd Item Specification: Identify and describe characteristics of waves: wavelength, frequency, amplitude and speed.

Depth of Knowledge Level 1

1. Use the diagram below to answer the following question. Line A best describes the wave’s

2. crest.
3. trough.
4. wavelength
1. Use the diagram below to answer the following question. Line A best describes the wave’s

1. trough.
2. period.
3. equilibrium.
4. amplitude.

Depth of Knowledge Level 2

1. Use the diagram below to answer the following question. Which interval represents one full wavelength?

1. Point A to Point C
2. Point B to Point D
3. Point A to Point G
4. Point C to Point G
1. As a wave travels between two points in a medium, it transfers
1. energy only.
2. mass only.
3. both energy and mass.
4. neither energy nor mass.

4th Item Specification: Identify the causes and effects of the Doppler Effect.

Depth of Knowledge Level 1

1. Which of the following is correct about the Doppler Effect?
1. The effect is observed as waves bend around solid objects.
2. It occurs as waves enter a new medium, such as going from water to air.
3. It is an observed change in pitch when either the sound source or the listener is in motion.
4. It is the change in wavelength as sound waves enter a medium and are reflected at the boundary.
1. Imagine that you are standing on a corner when a fire truck with sirens screeching approaches you. Which of the following is true?
1. As the truck approaches you, the siren’s pitch seems higher to you.
2. The siren’s pitch seems lower to you as the truck approaches.
3. As the truck passes you, the pitch seems to increase in intensity.
4. The siren’s pitch remains lower then higher as it approaches and passes you.

Depth of Knowledge Level 2

1. The reason a fire truck’s siren sounds HIGHER in pitch as it approaches you is because the truck pushes the sound waves together so that the sound wavelengths in front of the truck get shorter. This causes
1. frequency to increase which increases the pitch.
2. velocity to decrease which increases the frequency.
3. frequency to decrease which decreases the pitch.
4. wavelengths to elongate increasing the pitch.
1. The reason a fire truck’s siren sounds LOWER in pitch as it passes by is because the truck pushes the sound waves together so that the sound wavelengths in front of the truck get shorter. This causes
1. frequency to increase which increases the pitch.
2. velocity to decrease which increases the frequency.
3. frequency to decrease which decreases the pitch.
4. wavelengths to elongate increasing the pitch.

5th Item Specification: Understand the relationship between velocity, wavelength, and frequency.

Depth of Knowledge Level 1

1.  The frequency of a wave represents the
1. wave amplitude divided by the period of the wave.
2. wave crest in relationship to the wave trough.
3. number of waves to pass a certain point in a given time.
4. loudness of a sound passing through a medium.
1.  Wave velocity refers to the
1. product of the wavelength and the frequency.
2. ratio of the wavelength and the frequency.
3. wavelength in meters per second.
4. period of the wave divided by its intensity.

Depth of Knowledge Level 2

1. The wavelength of a wave can be calculated by
1. multiplying the velocity times the frequency.
2. dividing the velocity by the frequency.
3. multiplying the amplitude by the frequency.
4. dividing the frequency by the velocity.
1.  The frequency of a wave can be calculated by
1. multiplying the velocity times the wavelength.
2. dividing the velocity by the wavelength.
3. multiplying the amplitude by the wavelength.
4. dividing the frequency by the velocity.

6th Item Specification: Understand the difference between transverse waves and longitudinal waves.

Depth of Knowledge Level 1

1. In TRANSVERSE waves, the wave energy moves
1. parallel to the wave vibrations.
2. perpendicular to the wave vibrations.
3. opposite to the wave vibrations.
4. in the same direction to the wave vibrations.
1. In LONGITUDINAL waves, the wave energy moves
1. parallel to the wave vibrations.
2. perpendicular to the wave vibrations.
3. apart from the wave vibrations.
4. at right angles to the wave vibrations.

Depth of Knowledge Level 2

1. Sound waves are
1. transverse waves because their vibrations are perpendicular to the motion of the wave’s energy transfer.
2. transverse waves because their vibrations are parallel to the motion of the wave’s energy transfer.
3. longitudinal waves because their vibrations are perpendicular to the motion of the wave’s energy transfer.
4. longitudinal waves because their vibrations are parallel to the motion of the wave’s energy transfer.
1. Electromagnetic waves are
1. transverse waves because their vibrations are perpendicular to the motion of the wave’s energy transfer.
2. transverse waves because their vibrations are parallel to the motion of the wave’s energy transfer.
3. longitudinal waves because their vibrations are perpendicular to the motion of the wave’s energy transfer.
4. longitudinal waves because their vibrations are parallel to the motion of the wave’s energy transfer.

Constructed Responses P.8.C.2

1. Sound is a form of energy that is transmitted through vibrations
1. Describe how sound waves are affected by their frequency and the medium through which the sound wave passes.
2. A science fiction film shows an explosion in space that is heard by the space travelers on board a spaceship.  Critique the correctness of this portrayal providing evidence for your argument.

Content Benchmark P.8.C.2

Students know vibrations (e.g. sounds, earthquakes) move at different speeds in different materials, have different wavelengths, and set up wave-like disturbances that spread away from the source uniformly.  E/S

1. A, DOK Level 1
2. B, DOK Level 1
3. B, DOK Level 1
4. A, DOK Level 1
5. D, DOK Level 2
6. C, DOK Level 2
7. C, DOK Level 1
8. B, DOK Level 1
9. C, DOK Level 1
10. C, DOK Level 2
11. D, DOK Level 2
12. B, DOK Level 2
13. D, DOK Level 1
14. D, DOK Level 1
15. D, DOK Level 2
16. A, DOK Level 2
17. C, DOK Level 1
18. A, DOK Level 1
19. A, DOK Level 2
20. C, DOK Level 2
21. C, DOK Level 1
22. A, DOK Level 1
23. B, DOK Level 2
24. B, DOK Level 2
25. B, DOK Level 1
26. A, DOK Level 1
27. D, DOK Level 2
28. A, DOK Level 2

Constructed Response 3-point Answers and Score Rubrics:

 3 points Response addresses all parts of the question clearly and correctly. Student response indicates an understanding that frequency is a measure of the regularity of passing sound waves and directly relates to the pitch of the sound, where a greater frequency results in a higher pitch. Student response also indicates sound is a mechanical wave, sound can only travel through a medium, and sound travels fastest through solids, then liquids, then gases. Sound is not transmitted through the vacuum of outer space. A student example might include bell ringer in a vacuum and observed lack of sound or a similar example. 2 points Response addresses all parts of the question and includes only minor errors. 1 point Response does not address all parts of the question. 0 point Response is totally incorrect or no response provided.

Content Benchmark P.8.C.2

Students know vibrations (e.g., sounds, earthquakes) move at different speeds in different materials, have different wavelengths, and set up wave-like disturbances that spread away from the source uniformly.   E/S

Intervention Strategies and Resources

The following is a list of intervention strategies and resources that will facilitate student understanding of this benchmark.

1. Exploring With Sound

This site gives students directions for a simple experiment that describes how sonar works.  A maze is created inside a shoebox with blocks of wood.  Using marbles a person figures out where the blocks of wood are located by listening to the sound.

To access this activity go to http://www.tryscience.org/experiments/experiments_begin.html?sound.

2. How Speakers and Radar Work

The How Stuff works website has some excellent discussions about common items that demonstrate scientific principles about waves. For example, the site has a thorough description of how speakers’ function is provided and numerous illustrations are included.  The article briefly explains the basics of sound and how the ear interprets sound.

To interesting discussion can be found at http://www.howstuffworks.com/speaker1.htm/printable.

Also at the How Stuff Works website is a complete description on how radio detection and ranging (radar works) and its uses are presented in this article.  The piece goes on to explain echo and Doppler shift.  Many useful links are given at the end of the article.

3. What Do We Mean By Crackling?

This is an interesting interactive site that describes things that crackle, such as paper, Rice Krispies™, earthquakes, and magnets.  You actually listen to the crackling noise and then simple demonstrations are supplied along with some complex experiments to try.

To access this activity, go to http://simscience.org/crackling/index.html.

4. Experiment With Sonar

Sonar is the use of sound waves similar to radar. NOVA, a science program on PBS,  has developed a great website that discusses sonar, including a wonderful animation illustrates how sonar works showing what you would “see” on a lake bottom or sea.  The NOVA site then provides a brief explanation, with images, on the uses of sonar.

The link to the visualization can be accessed at http://www.pbs.org/wgbh/nova/lochness/sonar.html

5. Exploratorium Activities about Waves and Sound

The Exploratorium Science Museum in San Francisco has several terrific activities for students to learn about science. In one activity, directions are given to create a musical instrument called a Bonko.  The site provides a clear explanation on what is going on with sound in the activity and how the instrument works.  A cultural connection provides information on different countries that use an instrument similar to the Bonko.

To access this activity go to http://www.exploratorium.edu/science_explorer/can.html

Also at the Exploratorium site is an activity which allows students to create an ‘Ear Guitar.” Clear directions are provided at this site, along with an explanation about the instrument works and the underlying principles of sound waves.

The Ear Guitar activity is found at http://www.exploratorium.edu/science_explorer/ear_guitar.html

Another fantastic site by the Exploratorium showing the application of sound in music.  The site is interactive with demonstrations, movies, and interviews.  Students will find the site engaging and interesting with the ability to create music in some of the interactive modules.  The history and culture of some musical instruments is also explored.

To access this site, go to http://www.exploratorium.edu/music/exhibits/index.html

6. What Is Seismology and What Are Seismic Waves?

The Michigan Tech Department of Geology has developed a tutorial for students on seismic waves. This site, called “UPSeis” provides a good overview for middle school students by describing earthquakes and their associated wave properties in nice detail.

Go to the  UPSEIS site by clicking on http://www.geo.mtu.edu/UPSeis/waves.html.

7. Oceans Alive! – Water On The Move – Wind and Waves

The Museum of Science has an excellent site using ocean waves as an example to demonstrate the scientific principles of waves.  There is a concise explanation of a wave’s characteristics.  If you investigate the web site further a good deal of information is given on oceans.

To access this site, go to http://www.mos.org/oceans/motion/wind.html

8. NOAA Ocean Explorer:  Sound in the Sea

This site provides brief description of the characteristics of waves is provided then ocean acoustics is explored in depth.  There is a wonderful collection of sounds from the sea and you can listen to various whale sounds, ship sounds, earthquakes, and volcanic tremors.  The technologies used for ocean acoustic monitoring are explained.  Biographies are provided of all the different scientists involved in the project.  The monitoring of global oceans through underwater acoustics is explored in depth.

To access this site, go to
http://www.oceanexplorer.noaa.gov/explorations/
sound01/background/acoustics/acoustics.html

This web site contains a selection of audio files that were recorded underwater, related video and animations, and other images of ocean sound.  The site shows how sonar, echolocation, and sound waves work.

To access this resource, go to http://www.oceanexplorer.noaa.gov/gallery/sound/sound.html