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U.S. Navy Museum Cold War Gallery Lesson Plan
Ship, Submarine, and Sea Creature Sounds in the Sea
Developed by Janice Cunningham, Berkeley County School District, SC
2012 Naval Historical Foundation STEM-H Teacher Fellowship
 
 
  Instructional Goal:

Teacher Help
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Download Lesson Plan Resource Kit by clicking icon
Explore sound waves and their applications, discovering the many aspects of sonar technology to understand how sonar signals help submariners determine where they are, without seeing, and also to find the location of other ships and submarines. This is a similar process to whales and dolphins navigating their ocean world. In this unit lesson the student will:
  • Practice creating and measuring a model of an ocean seabed or sea floor
  • Practice measuring depth
  • Use descriptive words for what they created and what they observed from a depth model
  • Use tactile (hands-on) strategies, as well as calculating logarithms, graphing logarithmic equations, and calculating radical equations used in submarine sonars
Background:

Similar to radar, instead of sending out radio waves, researchers and sonar technicians use active sonar by sending out (transmitting) sound waves and listening for a return echo. In measuring the time it takes for these sound waves to travel to an object, bounce off (reflect), and then return to the sonar transmitter (hydrophone), it is possible to calculate distances. Active sonar detection can also be used to accurately map about 2/3 of the Earth that is underwater. Only about 5% of the underwater surface of the earth (topography) has been accurately mapped.

SONAR stands for SOund wave Navigation And Ranging. RADAR stands for RAdio wave Detection And Ranging. SONAR and RADAR are two methods that submarines and ships can determine their position as well as determine another ship's position. Passive sonar, evaluating only the sound emissions from another ship, submarine or sea creature, can also be used to determine the position of the other ship, submarine or ocean dweller. Active sonar can also be used in very cold waters where ice and icebergs are present, to safely navigate underwater by displaying the underwater topography on computer screens.

For a basic tutorial on Sonar Propagation, see the teacher help section U.S Navy training document:  "Sonar Propagaton"

For example, in shallow water, the sound energy is contained in a cylinder, and the energy spreads out within the cylinder as shown below, making the sound quieter with range (R). When the acoustic energy reaches either the surface or the bottom of the ocean, it is generally reflected back. At long range, all of the acoustic energy will tend to confined between two planes, one at the surface and the other at the bottom. Therefore, the energy can no longer spread out like the spherical spreading case in deep water (see activity 2), but now becomes cylindrical spreading.

Cylindrical spreading diagram


The area over which the energy is distributed now varies directly with range, R. The energy of the sound dissipates (transmission loss) according to the formula: 
TLcylindrical = 10 Log( R).

Cylindrical spreading formula


Resources:

"Sonar Propagaton" tutorial
US Navy website
The Naval Sea Systems Command, coloring books, posters, STEM information
Microwave, Radar and Sonar
Whale Sounds
Association for Unmanned Vehicle Systems International (AUVSI), Start a RoboSub Competition Team

Measure the Sea Floor: Depth of the Ocean Using a Can or Tissue Box Model

Objective:

Students will create a miniature model of an ocean floor. Each student will then measure the depth of the ocean: the distance between the model ocean surface and the model ocean floor.

Materials:

Empty shoe boxes, empty cans, grid paper, pencils, food coloring, playdoh, or homemade flour clay, sand, dirt, small pebbles, small shells, glue paste, clear tape, scissors, clay, ruler, dowels, measuring tape.

Instructions:

Prepare in advance. Have the students beforehand collect clean tin cans, or small tissue boxes until you have enough for each student. If you do not want to use playdoh or clay, you can use paper-mache strips of flour, water, newspaper to create a quick drying ocean floor bed to measure. Paint is not needed but if your students want to add color to their ocean floor models, they can. Students can take food coloring and dilute it to get a variety of inexpensive paint coloring.

Have students measure the area of the container they are using. Students can even calculate the volume of the container using Volume of a cube formula, V = s3; volume of a rectangular prism, V = lwh; volume of a cylinder, V = ∏ r2h.

Have each student use one container. Each student will use flour paste, newspaper, playdoh or clay, rocks, gravel, sand, small shells to create an ocean floor on the bottom of the container. Have students make a non-flat surface: mountains, plains, valley, ridges, volcanoes, sand bottoms, rocky outcrops, coral, or bay mud -- and let dry.

Each student will create a miniature ocean floor for another student in the class to measure with the ruler, straw or dowel. To prepare for the bottom ocean floor measurements, measure the surface base length and width, or the diameter of the circular can. Take grid paper and trace their box, container, or can dimensions on the graph paper, then lightly attach this grid paper to the top of the container.

Next day, have students switch their containers with another student. The teacher can number each container randomly and have other students pick a container number out of a hat, that is not his or her own.

Have each student cover the outer top surface with a tissue paper, or light penetrable material. Have students take their straws, rulers or thin dowels to measure the length from the outer top surface to whatever it is touching on the ocean floor. Make certain that the straws or dowels are being placed vertically straight so that they can get an approximate reading. Remind students that they are to take these reading without actually looking into the container. They are taking the readings as if they are in a submarine and using sonar equipment to get this reading. Have students record these measurements onto the attached grid paper. Some students may even draw a topographical map on how the sea bed is formed. After the student is finished, have student uncover the container and record what they see. Have students compare what they see to what they were able to record on their grid paper.

 
 

 

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