This lesson introduces students to the submarine as a means of travel under the sea, and to the challenges humans face when traveling underwater. Students will learn that submarines, like other boats, can travel on the surface of the sea, but they can also submerge to travel underwater. They will look at pictures of submarines on National Geographic's K-19 and Other Subs in Peril Web site, and review the basic construction of submarines and the underwater environment in which they travel. Students will conclude by creating a mural in their classroom featuring a fleet of their own model submarines and examples of marine life that might be encountered on a journey under the sea.

Geography, environmental science

Standard 13: "How the forces of cooperation and conflict among people influence the division and control of Earth's surface"

One to two hours

• Computer with Internet access
• Children's dictionary
• Materials for arts and crafts
• Wall map of the world
• Blank Xpeditions outline maps of the world, one for each student

Students will

• consider the challenges of building submarines so that human beings can survive underwater;
• use a dictionary to define the words "submarine" and "fleet";
• locate the United States and Russia on a world map;
• identify the components common to most submarines and their uses;
• build a model submarine and give it a name and number; and
• create a mural showing the "Classroom Fleet" in an undersea environment.

Ask students if they have ever tried to swim underwater. If so, how did they breathe? Did they have to hold their breath until they ran out of air? Inform students that all animals need oxygen to survive. Ask the class to take a few deep breaths. They will notice how air fills their lungs when they inhale and gets pushed out when they exhale. This action gives their bodies the oxygen they need and gets rid of carbon dioxide.

Ask students to consider the challenges human beings face in order to travel underwater. Can they survive without air to breathe? What about food? Also, how can they keep themselves or their boat underwater for a long period of time? Remember, boats are usually designed to float on top of the water—not to sink below it. Introduce the submarine as a means of travel under the sea.

Using a dictionary, define the word "submarine." Break the word down to show students that it literally means "under the sea." The definition may also include a reference to the "submarine" as a type of sandwich. In this case, ask students why this might be. What is it about the sandwich that is similar to an actual submarine? This will lead students to a discussion about the submarine's shape. Have students discuss what it is that makes the submarine different from other boats. Look at the pictures of submarines on National Geographic's K-19 Web site to give students an idea of what submarines look like in the water.

Next, use the dictionary to look up the word "fleet." Inform the students that the United States and Russia have the two largest fleets of submarines in the world. Help students identify the United States and Russia on a wall map, and ask them to color in these countries on their own blank outline maps of the world.

Tell the students that they are going to build their own fleet of submarines for the classroom. Show the class this diagram of a submarine with the main parts labeled: the hull, ballast tanks, sail, propeller, and periscope. Refer again to the images of submarines on K-19 and Other Subs in Peril and see if students can point some of these features out. Briefly explain the purpose of each part:

• The submarine's "hull" is the largest part of the boat. It is actually composed of two parts: an inner hull and an outer hull. Almost all of the submarine's activity is contained in the inner hull. In particular, this is where crew members work, eat, and sleep. The inner hull contains the engine room and the machinery that makes clean air for the crew to breathe and fresh water for them to drink. This hull is designed to resist pressure when the submarine is underwater. Between the inner hull and outer hull are a submarine's "ballast tanks." Explain to the students that these tanks cause the submarine to submerge when filled with water and to surface when filled with air.
  
  
• Explain that a submarine's "sail" is used to control the submarine when it is on the surface of the water. Sometimes this part is referred to as the "fin." What animals can students think of that have fins? Point this out as an example of how submarine travel is associated with the fish that live in the sea.
  
  
• The "propeller" is turned by the submarine's engine. This enables the submarine to move forward or backward, gliding like a fish through the water.
  
  
• Finally, introduce students to the "periscope." This is the part that gives the captain and crew a view of the sea and sky when a submarine is positioned just below the surface of the water. Tell the students that, when the submarine dives deep beneath the surface, the crew relies on other methods, such as sonar, to guide them through the dark water.

Review what the class has learned about submarines. Discuss how submarines are different from other boats. In what situations might submarines be more useful than a boat that cannot go under water?

Have students construct their own submarines as a classroom activity by drawing pictures or creating three-dimensional models. Prompt them to identify the different parts of their submarines and the purposes they serve. Remind them to consider which parts are needed for a submarine to submerge and travel under the sea.

Tell students that each United States submarine has both a name and number to identify it. Ask students to choose names and numbers for their model subs, pointing out that subs are frequently named after famous people or places, or after fish or other animals. Have them write the names and numbers they choose on their models so they can identify them.

Create a mural displaying the "Classroom Fleet" in an undersea environment. Have students attach their drawings or models to the mural. Then, have them visit the online coloring book to obtain images of ocean life for the students to add to their underwater world.

• Have students experiment with how a submarine's ballast tanks work. Conduct the Build and Maneuver a Submarine classroom experiment to show how a submarine sinks and surfaces by filling its tanks with water or air.
  
  
• Read, "The Magic School Bus on the Ocean Floor," by Joanna Cole and Bruce Degen (Illustrator). Then, take the students on an imaginary underwater adventure in their classroom. Have them point out the different kinds of underwater life they encounter on their journey.

Dive, Dive! An Introduction to the History and Technology of Submarines
National Geographic: K-19 and Other Subs in Peril
National Geographic: Coloring Book
Office of Naval Research: SubmarinesHow They Work