sonar (1 hour)

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Addresses NGSSLevel of Difficulty: 3Grade Range: 3-5

OVERVIEWIn this activity, teachers will create a mysterious topography using small boxes inside a copy paper box. Students will simulate sonar by inserting wooden skewers into holes in the box lid to investigate the unknowntopography. Students will use that information to make a contour map of the mysterious topography.

Topic: Sonar and two-dimensional mapping of a 3D landscape

Real-World Science TopicsUses of sonar:

• Submarines use sonar to detect other vessels

• Oceanographers use sonar to map the ocean floor

• Fishermen use sonar to locate schools of fish

• Geologists use sonar to locate oil and gas deep underground.

• Ultrasound uses the principle of sonar to investigate inside the human body.

ObjectiveStudents will gain an understanding of the reflection of sound and how it is used by sonar.

NGSS Three-Dimensions

SONAR (1 HOUR)

Developing and Using ModelsModeling in 3–5 builds on K–2experiences and progresses tobuilding and revising simplemodels and using models torepresent events and design solutions. • Develop a model using ananalogy, example, or abstractrepresentation to describe a scientific principle.

Analyzing and Interpreting Data

Analyzing data in 3–5 builds onK–2 experiences and progressesto introducing quantitative approaches to collecting dataand conducting multiple trialsof qualitative observations.When possible and feasible,digital tools should be used.

Science and Engineering Practices

PS4.A Wave Properties• Waves, which are regular patterns of motion, can bemade in water by disturbingthe surface. When wavesmove across the surface ofdeep water, the water goesup and down in place; it doesnot move in the direction ofthe wave except when thewater meets the beach.Waves of the same type candiffer in amplitude (height of the wave) and wavelength(spacing between wavepeaks).

Disciplinary Core Ideas

Patterns• Similarities and differences in patterns can be used tosort and classify natural phenomena. Similarities anddifferences in patterns can be used to sort and classifydesigned products.

Crosscutting Concepts


SONAR (1 HOUR)

• Analyze and interpret data tomake sense of phenomenausing logical reasoning.

Background Information

SONAR stands for Sound wave Navigation And Ranging. It is technology used to locate objects underwater.Sound waves are emitted into the water. Sound waves are used because they travel farther in water thanelectromagnetic waves. The time it takes for the sound to bounce off an underwater object and return to the surface is measured. Using this time and the speed of sound, the distance travelled by the sound can becalculated. If you divide this time in half, you will know the depth of the object that reflected the sound wave.

Key Vocabulary

Contour map – a map showing lines that connect points of the same height; the closer together the lines, the steeper the change in heightEcholocation –when animals create sounds which are sent out into the environment to bounce off of nearbyobjects and return, animals can use the echo to find food and maneuver in dark places

Materials Needed for the Student Activity

• One ping-pong ball for demonstration

Each group will need:

• Copy paper box

• Wooden skewer

• Several small boxes

• Ruler

• Paper

• Crayons

Teacher Preparation

In the weeks prior to the activity, collect copy paper boxes and small boxes of many different sizes. Pieces of styrofoam, books, or reams of paper can also be used.

You will need to create the mysterious landscapes incopy paper boxes before the students arrive. Decidehow many students you want to work in each group.You will need one copy paper box for each group. Draw a grid on each copy paper box top. Draw a line 1 inch from one edge of the box top, and then every 2inches until you reach the other edge of the top. Repeatin the opposite direction. Use a wooden skewer to pokea hole at every spot the lines intersect. This will result in54 holes.


SONAR (1 HOUR)

In each copy paper box, arrange a series of smaller boxes to create the unknown landscape. Tape the lid on the box so that students will not open it during the activity.

Grade 4 – Decrease the number of holes in the box top and create only three different heights in the unknown landscape.

Grade 6 – Increase the complexity of the landscape. Create several different heights in the copy paper box.Students can also draw the grid on the lid and poke the holes.

During class the day before the activity, give the students the following homework: Go into a small bathroom, close the door, close your eyes, and yell your name! Then, go to the biggest room in your house(or outside), close your eyes, and yell your name again. Take note of how your voice sounds in each location.


STEPS FOR SONAR

1. Warm-up Activity: Discuss the “homework” activity that the students did the night before. Did theirvoices sound different in a small space versus a large space? Ask them to describe their observations. Weoften rely on our senses of sight and touch, but we can learn a lot about our surroundings from our senseof sound. Some people who are blind actually make clicking noises and listen for the clicking sound tobounce off of walls and objects in order to find their way around. They can tell if the sound is bouncingoff a wall or an open doorway. [ you can find videos and articles about this to show the class]

What is a reflected sound wave called? An echo. In a very large room, like a gymnasium, the sound wavesof your voice must travel much farther before they can reflect off a surface and return to your ears. In asmall room, your sound waves reflect off the walls instantaneously.

Tell the class we can’t see the sound waves travelling through the air, so you will use a ping pong ball torepresent sound waves. Bounce the ping pong ball off a wall. It bounces off and returns to you, just likethe sound of your voice. Bounce the ball off a wall that is farther away. Now, it takes longer for the ball to reflect back to you.

1. Distribute the Student Handout. Scientists use echoes to “see” places that we can’t see with our eyes.This is called sonar. Oceanographers use sonar to map the ocean floor. They send a sound signal downinto the water, it bounces off the bottom of the ocean floor and comes back up. They measure theamount of time it takes to come back. The longer it takes for the reflected sound wave to return, the farther it must have travelled. For example, look at the pictures on the Handout. When the boat is in position 1, it will take longer for the reflected sound wave to reach the boat because the ocean is deeperat that point. At position 2, the sound will take less time to return to the boat because it did not need totravel as far.

POSITION 1 POSITION 2

Surface of water

Ocean floor

3. Tell the class they will be simulating sonar to discover a mysterious landscape. Show them a copier box.Tell them the landscape is in the copier box. Explain that they will “send down a signal” into the box atmany locations. Instead of sending a sound signal, they will be sending down a wooden skewer to measurethe distance from the surface (copier box lid) to the landscape below. Tell them to push the woodenskewer into a hole. When they pull the skewer out, use their fingernails to mark how far the skewer wentin. Then use a ruler to measure how far the skewer was inserted. Tell the students what units with which to make their measurements. You may want to tell students to round to the nearest inch, half inch, or centimeter in order to simplify the activity. All the distances will be recorded in the table on the StudentHandout. Break the class into groups and let them collect data.


STEPS FOR SONAR

4. Once all groups have finished collecting data, explain that they will now make a two-dimensional map of the three-dimensional landscape that they explored. Follow the instructions on the Handout.

5. Wrap-up Activity: Have each group share their contour map with the class. Tell the class sonar was developed after the Titantic disaster to help locate icebergs. Ask the students what else oceanographersmight look for with sonar. Answers may include a submarine, shipwrecks, a coral reef, a school of fish, an underwater volcano, or a huge valley created by tectonic plates colliding.

Extension Activity

Divide the class into groups to research how bats, whales, and dolphins use echolocation.

Sources

http://projectniu.org/lesson-plans/science/http://www.divediscover.whoi.edu/http://www.whalefacts.org/


SONARSTUDENT HANDOUT

Name:

Date:

A reflected sound wave is called an _______________________.

In the figure below, the boat is sending a sound wave down to the ocean floor. It will reflect off the oceanfloor and return to the boat.


Surface of water

Ocean floor

Which position is the ocean the deepest?

Which position will the sound wave take more time to return to the boat?

What can oceanographers calculate using the time the sound wave travelled?

Collect data from the sonar activity in the following chart. Record the length of the skewer that could be inserted into the box at each hole.



Choose a crayon for each different height you measured. Use each crayon to draw boxes connecting pointsof the same height. Color in these boxes.

Make a key below to show what depth each color represents.

Some boxes are still white. Divide each white box in half, coloring each half with the appropriate color. You are creating a contour map.

Show your contour map to your teacher. Your teacher will then remove the top off the copier box. How well does your contour map match the landscape in the box?

color depth


SONARTEACHER HANDOUT

A reflected sound wave is called an echo.

In the figure below, the boat is sending a sound wave down to the ocean floor. It will reflect off the oceanfloor and return to the boat.


Surface of water

Ocean floor

Which position is the ocean the deepest?

Position 1

Which position will the sound wave take more time to return to the boat?

Position 1

What can oceanographers calculate using the time the sound wave travelled?

How far the sound traveled/ the depth of the ocean at that position

Collect data from the sonar activity in the following chart. Record the length of the skewer that could be inserted into the box at each hole.




SONARTEACHER HANDOUT



Some boxes are still white. Divide each white box in half, coloring each half with the appropriate color. You are creating a contour map.

Color Depth

Red 9 inches

Yellow 2.5 inches

Blue 3.5 inches

Green 5 inches

Purple 1 inch


SONARTE4ACHER HANDOUT

Show your contour map to your teacher. Your teacher will then remove the top off thecopier box. How well does your contour map match the landscape in the box?

For the example landscape shown in the picture above, the contour map will look like this:

sonar (1 hour)

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